Can I recommend that each guide (combat and assassination) be updated to include this bit of information. Until now, I thought that having both expertise and spell hit cap for combat was required for max dps.

This means that once combat rogues get to the expertise cap and yellow hit cap, then move any extra to haste?

So, my question is...
In the current content is there any PvE usage of Smoke Bomb at all?

As a combat rogue, when im starting a fight, I find myself rupturing, slice and dicing, hitting one sinister strike, and then hitting my killing spree. I know i've read that I should be using KS when i've got my 30% buff up, but even from the beginning of a boss fight, should I be holding it back? Assuming i'd be able to use it once or even twice more in the boss fight if I use it in the beginning as opposed to waiting for my buff.

If you know for an absolute fact that the fight will be of the precise length that means waiting on Bandit's Guile will cost you a KSp, it may be worth it; however, if you don't know the fight length that precisely (and you usually don't), its generally better to wait. This may cost you a KSp over the course of the fight, but that may not actually matter. For instance, which does more damage, 4 KSps doing +30% damage, or 5 doing only base damage? 4 * 1.3 = 5.2 > 5, so in fact its okay to miss one as all the others hit harder.

That said, in practice randomly spaced KSp's won't do 100% damage all the time, but when you work out how long you have to wait for Bandit's Guile to stack up versus how much damage you gain by waiting, it usually turns out to be worth it.

A while back KS & BG's modifiers didn't stack and since KS' 20% was better than the 15% from BG, it was actually better to use KS asap. Now BG got buffed to 30%, KS does a mere 8.3% more damage, is that small change really enough deny KS at the risk of losing one though? Even if you knew the exact fight length there is still some rng to combat cp/energy generation that can easily get you that extra finisher or two and get your KS off cd.

I'm pretty sure its since been confirmed that KSp now works properly with KS. If that's not the case, then that would indeed mean you should KSp immediately; but I don't believe that to be the case.

Assuming, however, it works the way I think it does: yes, you risk losing a KSp. However, for a fight of unknown length, the expected value of waiting is higher than the expected value of going immediately. That is: some portion of the time you will lose a KSp. In this case, you will do somewhat less damage. The rest of the time you will do the same number of KSps, and they will hit harder, resulting in you doing somewhat more damage. If you work out how much damage you gain and lose, and how often each case is expected to happen, it works out that on the average, you will do more total damage by waiting than by going immediately.

I'm sure this was answered at some point in the past, but the answer isn't here or in the threads for combat or assassination. I understand that they say to use IP on MH and DP on OH, but it doesn't exactly say why, and I was wondering what the exact reason was?

I'm hoping to get a more in-depth answer than "because the sim says so," but if that's truly the case and the only reason, ok. The question arose in my mind because of the way I understand the PPM system to work; that is, instant on the main hand or instant on the offhand, the same number of instants should be applied over a given timespan even with different weapon speeds, so wouldn't the flat chance of deadly applying - and the built-in poison-proc for the other weapon - cause more instant procs than otherwise due to the increased amount of hits with the main hand?

Ok, that answers it for assassination, and honestly I can't believe I overlooked that. However, it doesn't answer it for combat, which uses significantly more main hand-only attacks.

The difference between the MH and OH speed is also significantly larger when using Combat weapons (typically 2.6/1.4). This just means that having Deadly Poison on the OH is even more important.

It really doesn't. Combat wants to use slow/fast anyway (because of Combat Potency), which, when coupled with Main Gauche procs, means you actually get fairly similar number of attacks from each hand. Hence, you want the slower weapon (with its higher IP proc rate) to have IP, and the faster weapon to have DP.

It is and they are. Presumably during the next actual patch (as opposed to hotfix).