I haven't used Rage, so I'll take your word on that for now, but as for Guerrilla, I've done the math.
Single-wielding attacks cost 1 AP
Dual wielding attacks cost 2 AP.
Guerrilla adds +50% damage and the Sneak to make use of it costs 1 AP. That additional AP has to be factored into the cost, whether you use the attack on the same turn or the next one.
Using Guerrilla with 1 weapon does the damage of 1.5 attacks for the AP cost of 2 attacks.
Using Guerrilla when dual-wielding does the damage of 1.5 attacks for the AP cost of 1.5 attacks. (In other words, you're not any better off using it than you would be for using normal attacks).
It is only useful when attacks do not cost AP - as in you enter combat through a sneak attack.
You get 4 AP per turn, so entering Sneak the turn before instead of saving that AP for the next turn only is a net AP benefit if you have 3+ AP left at the end of your turn and would "lose" an AP when the 4 from the next turn is added to fill the 3 empty AP bubbles. If you have 1 or 2 AP at the end, Sneaking will prevent you from being seen, but it is one fewer AP than you would have had on the next turn.
Many people sometimes forget that while the burst damage of a dual wield rogue could be hire given skills and sneak attacks, the 1AP cost of 1h weapons allow for greater tactical flexibility. It's fairly easy to fit a 1AP skill/attack into any turn and still do a few other things, but it can be limiting to have to always require (plan for) 2AP of dual wielding.
While the bonuses from dual wielding can be a turning point in decisions, I find that the advantage mitigated by the fact that characters will still be limited in tactical flexibility. The bonuses will make their burst damage higher and their skill effects powerful, but they will still be limited in how they can make use of them.
The ability to, assuming 4 AP a turn, get to:
- [attack/use skill/move from sneak->attack/use skill/move->attack/use skill/move->go back into hiding] is fairly strong
vs
- [attack/use skill/move from sneak->attack/use skill/move or attack/use skillmove from sneak->use skill -> go into hiding or ...] where you must decide what to commit to
Then you have to consider how useful Sneak is in combat and how powerful it is tactically. It prevents the enemy from targeting you that turn and lets you safely cooldown skills and position yourself.
The fact is: for those people that plan to sneak alot in combat Guerrilla is plenty useful. Could be better; warrios come to mind. But far from useless. Also, When using a rogue of some kind and initiating all your damage bonuses and then getting a crit, that +50% is very very non trivial.
EDIT: I was lazy and basically copied majority of this from my post in 1h vs dual wield :P Yay for Action Economy!
EDIE2: Also, also, shouldn't this thread be focused on grenades!? I'm so easily distracted! @.@
