That. Just ... that.

@Kbs

Your view of this is too narrow. Blizzard has gone out of its way to improve the synergy of certain talents. If it were just the case that the benefit to Main Gauche was the damage generated by the extra attack this point of view would be correct. However...

The mechanics at play here are thus:

-Many of our abilities base their damage on main hand weapon damage, these attacks require energy.

-Main Gauche increases your chances for an offhand attack to be granted when you deal damage with your main hand weapon. When we use abilities like sinister strike, we're using our main hand weapon.

- http://www.wowhead.com/spell=35542 (Combat Potency) Grants energy for successful offhand attacks.

-Placing http://www.wowhead.com/item=2892 (Deadly Poison) on your offhand weapon means, if that weapon is fast, and you're smart enough to put points into Combat Potency, you're increasing the application of Deadly Poison which means you're immediately doing more damage with Instant Poison.

-All of this adds up to more energy via Combat Potency which means more finishing moves because we have more energy to build combo points, which means a lot more damage.

In summary,

More wound poison.
More instant poison.
More energy.
More finishing moves.
More damage.

Offhand weapon damage is meaningless in comparison.

@ Luke

Haste.

You are very right in your analysis of the case for frequent OH attacks and their additional benefits, which is why we're so into fast OHs in the first place. But you are forgetting haste. Raw haste = faster weapon swings and leads to the procs you mentioned. Raw Haste also increases our passive energy regen too, giving an additional route for energy recovery.

Raw Haste rates much higher EP than Combat Mastery for a very valid mathematical reason.

@pryn

That is a very good point sir. I didn't take the time to break down specific stats and how they fit into these mechanics for just a couple of reasons. The main reason is the fact that the mechanics I mentioned exist independent of stats like haste. As a Combat Rogue you've chosen certain talents, and the Combat tree introduces unique abilities and mechanics. It seems too early in the expansion to know how stats will effect these.

It follows however that if there are limits, whether internal or imposed, that haste at a certain point caps and ceases providing additional benefit. Too, do we know yet that haste for certain provides more benefit than agility? Meaning the AP and Crit that agility provides may outweigh haste if we have to stack haste at the detriment of other stats.

Being that I'm not certain if haste would need to be stacked or if it's possible to have enough through gear alone I'll reserve judgment until I can look into it further (if there is enough data available).

In any case though aren't we talking about white damage? The benefits of haste that you mentioned only seem to affect a small amount of white dps. Meaning also the increase to energy return won't be reduced by a fast off hand. Can't we have our haste and stab with it too?

I foresee a return to EJ in my future.

@ Luke

*cough* Good point Madame! *cough*

I would recommend a return to EJ sooner rather than later. There is some pretty excellent work going on over there in the rogue community, as usual!

As for the haste causing faster melee swings, its all the same benefits you listed as being possibly attributed to Combat Mastery procs, so we are talking Combat Potency and poisons in addition to white damage. That being said haste doesn't come close to Agility and competes with Hit and Exp before their relative caps. Take a dive into the Combat Thread on EJ and I think you will find alot of food for thought.