Your question doesn't prompt a clear cut answer. And your post goes some way to outline why that's the case: You ask if it'd be worthwhile to not reforge expertise into haste when the latter is your only reforging option. Current theorycrafting says it isn't; you think it might be for encounters that aren't of the "hit-the-boss-for-six-minutes-straight" persuasion. The predicament is that current theorycrafting models to a large extent presupposes just that. As such, reactions outside that framework are situational and tend to be more dificult to model.

As you phrase it yourself: Your foundation for asking this question is anecdotal, and more than anything, the answer is situational. In some encounters, it might be, in others it might not. To that end, whether or not sticking with expertise is worthwhile is pretty much up to you. My suggestion would be to test it. Try to get an idea of your dps while target switching with both reforging strategies. If one works notably better for you, in the raid content your guild is currently going through, well, I guess that more than anything is your answer.

It's hard to imagine a situation where haste is the only option for reforging. If you are hit capped (spell of course) and have a piece of gear with exp/mastery, try reforging that to hit and reforging something else that you already reforged to hit into mastery instead. Sometimes you have to change quite a few pieces of gear to get hit close to the cap and still grab as much mastery as you can get.

Other than that, Onodrim gave a great non-condesending answer.

I have some doubts about this theory.

Take this example:
-you are nearly energy capping
-it remains 11 sec before your rupture falls off
-you miss your envenom with 4 cp so the envenom buff is active and you still have 4 CP

In most cases you can't rupturing or don't want to do it because the uptime is too high.
In that case, you are forced to use envenom. The other solution would be to wait for the end of the envenom buff but you will be ernergy capping. Therefore I believe using envenom is the best thing to do.

Correct me if I am wrong.

You're right, but as it's been discussed several times already, those one or two seconds of envenom do not cost you any CP, and are in essence, free damage. You've basically turned a 5 second envenom buff into a 6 second envenom buff.

Round and around we go with the expertise debate to what seems like no end. I believe it is a gross oversimplification for theorycrafters to assume the reported expertise stat weight in this thread to be anything more than a statistical mean across varying mechanics of the game. (Confirm / Deny?)

Expertise stat weights will vary depending on the individual boss fight mechanic (i.e. standing in front or behind the boss). To theoretically maximize your dps throughout a raid I would argue the necessity to gear depending on each encounter- one set with some expertise (how much would need testing but capping is likely less than optimal) and the other without expertise. If the ultimate goal is maximization of dps then this would be the only correct answer in the expertise debate – gear specifically for each encounter’s mechanic. This may only mean a couple of pieces to swap out in order to accumulate the optimal (#?) expertise when standing in front of a boss.

Considering the majority of raiders at this point do not have the option of having multiple gear sets it begs the question- what is the optimal amount of expertise to have for each raid instance? I would presume each raid would have a different answer due to mechanics of each of the fights. Obviously capping expertise is wrong but additionally claiming that zero expertise is equally as faulty. Due to the ridiculous amounts of testing that would be necessary to quantify the optimal median expertise for each of the three current raiding instances I’m assuming that is why most have answered “make your own choice” depending on your own gaming paradigms. At the end of the day, those that claim the answer is one or the other at all times are flat out wrong if the end goal is overall dps maximization.

(BTW first post here and how can I be more Elitist than arguing both sides are wrong )

Yes of course, but energy capping is a consequence of this theory that means waiting for the end of envenom if you cannot use rupture. As you said in most cases using rupture when an envenom is dodged is not possible.
I don't know if you see what I mean, I think we are saying the same thing in a different way anyway.

I used to use 1-2 CP ruptures in raid, and I noticed it was easier to apply rupture when envenom was dodged, but it's just my own experience, a feeling, not mathematics.

The difference between 0 expertise and capping expertise (as a non-gnome) is 781 expertise rating.

To put this in perspective. Unless I'm missing something, if you reforged mastery to expertise (starting at 0 to the cap) you would lose 0.2 ep x 781= 156.2 ep.

And I believe that ep = dps in a very approximate manner. So on a 20k dps gear set, you'd lose 156.2 dps by reforging to the cap because dodges annoy you.

And yes, on fights where you stack in front of the boss for any noticeable amount (Maloriak, Chimeron, Double Dragons, heroic rohash etc) that might even be a dps gain to cap expertise. I don't have the aptitude or ability required to figure that out.

Now the fact of the matter is that 156 dps on 20k is under 1% dps loss. In all honesty instead of people arguing that it's not a dps loss to gem/reforge for expertise, why don't we just say something like the combat guide does.

"Capping Expertise is approximately a 1% dps loss on standard fights, and likely less for any fight where you stand in front of the boss for any meaningful length, it is up to the individual rogue to decide if that dps loss is worthwhile to have a more consistent cycle and be able to focus more on fight mechanics"

That way everyone is happy. I mean to be fair, a more stable cycle will also let rogues focus more on environmental effects, and so there may even be a dps gain due to reduced user error.

I believe I may have misspoke. My understanding of expertise is that the contribution to dps is implicitly dependent on game play unlike other stats by reducing blocks/parries and therefore having an effect on damage/dps. If this is correct, the value of the stat would vary based on the position of attack e.g. worthless behind target / more successful attacks in front. If this is the proper understanding it would presumably lead to assigning separate EP weights on the stat dependent on position. This rationale is why I proposed swapping out a few pieces depending on the mechanic of each boss to gain/lose the expertise. Understandably difficult to model therefore the assigning 1 overall weight is the easiest way to boost the average player's dps (and we're all thankful EJ does so). The "debate" part is both positions (have it or don't) have validity that even the "endless trickle of dimwits" can see. Of course, I could be wrong and the EP weight is exactly 1.1 regardless of standing in front or behind the boss - I've just never seen a boss dodge/parry when attacking from behind.

Bosses don't parry from behind. They do dodge from behind. The 1.1 value assumes you're behind so only getting dodges. As discussed, the value does go up when you have to attack from in front. Of course, if you're attacking from the front, that's not the only thing that changes (as, for instance, you can't Backstab from in front) so I'd refrain from drawing too many conclusions about what happens in that circumstance. Particularly because while it does happen during some phases of some fights, its not common enough that I'd worry excessively about massively reoptimizing based on the possibility.

You should really put this on the front page. I was confused when I read the original guide, but am not anymore. Thanks.

Expose Armor is a DPS loss because you have to move an additional talent out of a DPS talent to make Improved Expose Armor 100% effective. As an Assassination rogue, the majority of your damage break down is magic (~55%-60% for single target). Because of this, the trade off of a DPS talent for a debuff that acts on less then half of your damage is a loss. Further, as mentioned in your quote, the same debuff is provided automatically by two of the tanking classes and in most raid environments, it is likely at least one will be present.