If they do stack at the moment, my guess is it is not intended and will be fixed. Common sense sais the glyph is supposed to replace the set bonus, and making them stack seems the wrong approach to that...

Why is erveryone so impressed with 4T8? I do see its value in 5 and 10 men play, where a tossed rejuv for someone taking splash damage is something very common. But i do not see it as very useful in the classical 25 raid (besides specially designed encounters with a lot of small, predictable or periodic raiddamage like Sapphiron, or 100%+ damage abilities like KT Ice Tomb, where immediate healing is prefered). All i gain through this setbonus is a single tick of immediate healing (about 2200 with the improved gear available then) after casting the hot. Judging from our usual raidhealing ('whack the healthbar' style) all ticks after the 0th will be wasted. Sure, this has something to do with healing discipline, but i really don't see the point right now.

4T8:
1. Increases the HPS and HPM of rejuv by 16%. Rejuv is about 25% of healing done in current content.
2. Is the first instant heal without a cd (along with talented renew).
3. Makes rejuv an excellent spot heal for targets with a small hp deficit.

How come 35% of my total healing in average is done by Rejuvenation ? Saying HoTs always overheal is false and counter-productive.

Turn off Recount, bring less healers and get some healing assignments going. "Real raiding" is not doing trivial content with 8 healers that could be done fine with 2.

Even if the target doesn't take more damage after the inital hit rejuvenation still costs only 371 mana so casting it is nearly never a bad idea. Also, raid damage tends to not be a one time deal like say decimate but usually more frequent and since rejuv lasts 18 seconds it's very likely to still be on that person. Not only that, it also enables swiftmend and the nourish bonus if the target takes some big spike or catches some nasty debuff.

The thing is that rejuv is extremely cheap, moreso if you use the idol (I'm not resto at the moment, wowhead comments put it at 340). This is the cheapest heal we have besides a 3.1 single-bloom. It is so cheap that you often cast it without a second thought, since it is a potent heal and it opens up an SM option.
As to reasons why people have lost a bit of hp:
1. ret pallies/spriests/locks - due to their mechanics. These classes are classic hot fodder and the stable heal of rejuv is better than the spike of a bloom.
2. Constant aura fights - this is where my 1st point applies the most. Rejuv already shines in these scenarios and the bonus is a significant bonus to it. Twilight torment also falls under this category.
3. Random raid damage - this will usually be more than a tick or 2 of rejuv. However, the ability to quickly spread out high HPM heals is still potent.

The point is that there is a big difference between someone at 100% hp and someone at 95% hp. Even if that person isn't likely to die, it is drawing attention from the other healers - why is this person not at full hp? Having a 1s gcd instant heal is a boon that I'm sure will be hard to give up.

Both bonuses are solid and nothing can really be faulted with them quite honestly. I somewhat wish we still had the -3 seconds on Swiftmend somewhere too alas.

Boosting RJ by 17% is great on paper but even better in reality where for the most part we never got the full effect. There are times where you will cast RJ on people with full HP in preparation of damage but for the most part you will end up using it after they have taken damage to which the set bonus will shine for getting you some of the healing done in advance.

If you look at it in the way that "the target only needed a 6k heal and they would have had that from RJ in 9 seconds anyway" then it just means they get the healing they need in 6 seconds and that there is less chance of that healing being sniped by someone else. Healing faster should not be dismissed so easily and while fair enough there are times when it does little to boost our Rejuvenations healing there are times when it does wonders.
Considering it boosts our current "best spell" which seems to be used even more in Ulduar than elsewhere you shouldn't really complain. and I could easily see 4T7 being used on fights with heavy focus on tank healing and 4T8 used on heavy raid damage encounters.

It would be nice in the end if the 4T8 bonus replaced the old RJ glyph (I doubt anyone would ever not take it then) but I think in the end set bonuses and glyphs will be used as a "popularity meter" for new talents in the next expansion. I could quite easily see an "Improved Swiftmend - Reduces the cooldown of your Swiftmend by 1/2/3 seconds and gives it a 33/66/100% chance to not consume the heal over time effect on the target" showing up as for the most part Swiftmend has been ignored via talents in in 3.x and how most things concerning it elsewhere have been eagerly met.

One way to make swiftmend a bit more attractive would be to just change the spell to read, "does not consume the HoT already on the target." We have a bunch of new, more attractive glyphs coming in 3.1, so we may end up ditching this glyph anyway. It would be nice to see the spell given some love, as it's remained the same since it replaced Innervate way back in vanilla WoW.

I can't imagine replacing the Swiftmend glyph in 3.1. I use swiftmend all the time, since I'm constantly throwing Rejuvenation everywhere. It's a fairly significant tool in my arsenal, which I would likely not use at all if it consumed a HoT. Even when I am glyphed for Healing Touch (which I do for Sarth10+3 and Undying runs), I still use Swiftmend all the time despite my direct heal casting so quickly. It's still a big heal which can be casted while moving.

While I would be happy if Swiftmend got some extra attention, I defintiely don't think it's necessary. I find the spell quite attractive in its current state + glyph.

Nature's Grace
The live version of this talent grants -0.5 seconds cast time on your next spell following a spell crit. In 3.1 this talent will grant 20% haste for 3 seconds after a spell crit.

This change is particularly interesting for the spell Nourish. This is because faster casts gain more out of this talent simply because they have the chance to proc it more often. With the added 25% crit increase to Nourish and the added Nourish glyph, this spell becomes more attractive to use.
With just a bit of haste, your Nourish drops below the base 1.5 second cast time, and its pretty easy to be able to cast 3 Nourishes once this buff procs. Of course any of those 3 casts can crit as well, and thus renew the duration of the buff.

To give a rough idea, with my current gear (haste focused) and without raid buffs my Nourish drops to ~1.1 sec cast with this buff. One of the fastest heals in the game.

So how valuable will crit rating gear be next patch? Until now i usually avoided crit in favor of haste or SP. But some changes seem to boost the value of crit:
1. If we allow LB to bloom more, the value of crit increases
2. 20% haste buff gained from from LB blooms, swiftmend but mostly regrowth and nourish. In particular the possibility of "rolling" this haste buff by critting often enough. The haste gain would also increase clearcasting procs.
3. The existing advantages which are living seed and of course the fact the heal itself is bigger when it crits.

How valuable will crit be for the new resto druid is something to think about, and as a side not Int as well is effected since it provides crit as well as buffing our mana regen which took a hit.

Crit used to scale best with Regrowth as it helped make the spell a more reliable crit which meant you could assume it would crit in safety rather than assume it would be a normal heal and get a bonus when it did crit. I would not count on either Nourish or Regrowth when cast being a critical in 3.1 with sub 50% chance and as such I would need to use it around the assumption it will heal for 5-6k not 8-9k (rough figures).

The previous version allowed you to generally be able to maintain the buff for whenever you needed it due to the 15 sec duration and also be a great addition in situations where you needed to spam Regrowth for short periods of time due to the -0.5 sec cast time on the majority of them. This meant that you could keep a pretty high uptime on the -0.5 sec which was fairly useful.

Nature's Grace now is questionably equal in short periods of spam with either Nourish or Regrowth but you now cannot maintain the buff beyond that short burst heal period for future use which is a notable downside. Combine that with the general mana nerfs meaning you honestly cannot do those spam periods very often and from what I have seen you do not need to do it that often either.

More time in 3.1 is needed to really see how things pan out but right now I am at the point where I would consider dropping Nature's Grace in favor of getting the last 3 points in Tranquil Spirit (which is bad but better to be safer with mana) until situations which require me to do these burst MT healing periods fairly often start cropping up.
With Nature's Grace removed the value of critical strike will plummet below normal levels but the positive side is that it makes haste have less issues as without the proc reducing us below the 1.0 sec GCD we can get slightly more benefit once past the softcap.