There could be absolutely no time between the Massacre hitting you, and the UF tick, which would kill you without even a global to save yourself with a DS, let alone a healer healing you. Far too risky to use it during the phase1 portions if you ask me.

I find the perfect strategy to be using UF + garg together during the first Feud (stacking up phase). It is then back off cooldown for the 0 healing phase burn at the end. During that first phase there are a lot of heals and cooldowns being used by your healers, so its alot safer. You may need to cancel it a bit early when the massacre at the end of the Feud phase comes, but its only usually a few seconds lost.

A note for you consider about using AMS in that phase - it also makes you immune to the hit debuff for those seven seconds glyphed. Another little point for the AMS section of the boss.

I was calculating items worth today and noticed something.

In the main post there is a section about gemming:
I had an item with blue socket and socket bonus 30 haste. Using the rule above I should gem 20str/20hit ?

Using the values from the main post:

Strength 3.09
Hit 0.78
Haste 0.75

40str gem = 3,09*40 = 123,6

while the 'right way of gemming' nets me

20str + 20hit + 30hst = 20*3,09 + 20*0,78 + 30*0,75 = 61,8 + 15,6 + 22,5 = 99,9

So am I misreading or should we gem orange/purple only when socket bonus is 20str or you need it for the meta.
Doing a little math it seems that the socket bonus for secondary stat should be at least 60 to get the same dps value as 40str gem has.

Unholy
•Scourge Strike now deals an additional 18% Physical damage done as Shadow Damage for each disease on your target. Up from 12%.
•Unholy Might now increases your Strength by 5%, down from 10%.

Will this be pushing 2H Unholy Above DW?

Runic Corruption procs while the aura is already active now add 3 seconds to the existing aura duration, instead of simply refreshing/overwriting the existing aura.

Machine gunning death coils seems like it will not be getting punished anymore, and given the proper circumstances it may even provide a dps boost (any time you are not GCD capped from Hero/Lust/Unholy Frenzy and your runes are all on cooldown). Could this also make the glyph of Death's Embrace worth taking to get your ghoul back up to full power during an important burn phase on a boss?

The Fury of Angerforge internal cooldown has been drastically reduced so this trinket will build up charges much faster.

Also looks like we may need to re-examine Fury of Angerforge to see if it is a viable alternative to existing BiS trinkets.

Might the runic corruption change justify increased points into ams? After the twin dragons with 3 pts in the talent, this change is actually pretty exciting.

Correct. If you use AMS (assuming you are glyphed for AMS) right before the first Caustic Slime during Feud, you will have it up for the second Caustic Slime as well, providing two full RP dumps, and making you immune to the hit debuff. Very important for that fight to help make the dps check on Heroic difficulty.

Using it about 1-2 seconds after the first has faded will make you immune for the 2nd and 3rd again providing 2 full RP dumps

I like these new meta gems, I was wondering why Blizzard had never put strength and agility based ones into the game back in Wrath. Critical strike rating has it's value, but 54 isn't enough to warrant the Chaotic anymore over 54 strength or whatever the stat will be I don't think, especially for Unholy where haste and strength are bigger stats. These gems will probably be best depending on your gear at the time of use, because otherwise you can start breaking haste cap and not needing it's benefit when that added strength might help instead. I guess I should get a spreadsheet going and see, but I get the feeling that the strength meta already beats out Chaotic for a DPS boost.

Secondaries simply don't stack up against Strength right now.

Let's say that they did hypothetically make that 54 strength and 3% crit. I can't imagine them actually giving us that much of a gain. However, if they did go with 54 strength, that would end up being best-in-slot for us.

To keep things simplistic, I used Op's 2h ilvl 259 stat weights, as that's the lowest stat weights for strength and, and 2nd-highest for crit:

54 Strength at 3.09 DPS per point would be 166.86 DPS
54 Crit at 0.62 dps DPS point would be 33.48 DPS

That would be a gain of 133.38 DPS.

So I've been running some sims. All simulations have been run using BiS gear with the exception of:
[Elementium Girdle of Pain] and some very minor reforging.

This sim reforged pretty much as suggested in the OP:
DPS 19399(+/- 1978)
Total Damage 6983.63m
RunicPower Total runic power used: 2433104 (3553 wasted)
Threat Per Second 12582
Generated in 20.72 s
Template 2H Unholy
Priority Unholy
Presence Unholy
Sigil
RuneEnchant
Pet Calculation True

This sim reforged for crit instead of expertise:
DPS 19438(+/- 1768)
Total Damage 6997.78m
RunicPower Total runic power used: 2411062 (3526 wasted)
Threat Per Second 12628
Generated in 20.22 s
Template 2H Unholy
Priority Unholy
Presence Unholy
Sigil
RuneEnchant
Pet Calculation True

Even an EP sim yields:
EP AttackPower 0.7 DPS
EP Strength 2.88
EP Agility 1.2
EP CritRating 0.62
EP MasteryRating 0.26
EP HasteRating 1.74 - this can not be correct.
EP ExpertiseRating 0.3
Before Melee Hit Cap 0.8
EP SpellHitRating 0
EP WeaponDPS 4.4
EP WeaponSpeed 510
EP 2T10 323
EP 4T10 560
EP 2T11 119
EP 4T11 261
EP 4T11 Tank 0

I can't imagine the belt alone is going to make enough of a difference to swing the value of expertise above crit, especially given my belt gives more haste.

My guess is that by buffing SS they are trying to remove DnD from our single target rotation and also nerf the UH DW viability.