There's some very interesting stuff on rogue builds in this thread.
And indeed CUN and daggers are the way to fly. Also some interesting stuff about lockpicking, how much you need for the hardest chests in this thread.
Respec mod is a rogues best friend! ;-)
IV: CONCLUSIONS
Dagger/dagger cunning is the clear DPS leader. Axe/dagger cun and longsword/dagger cun are about tied for 2nd place. The rest of the builds are pretty close in DPS, with the fullsize/fullsize builds lagging behind their fullsize/dagger counterparts.
Please bear in mind that this analysis assumes the same hit-rate across all builds, since I can't calculate real hit rates without knowing monster defense. In practice the cunning builds will likely hit less often than the other builds unless boosted by party buffs. Those who have played a high level cunning rogue says the hitrate difference is not large with the right attack rating boosts.
Also bear in mind that the cunning builds require three more talents than the str/dex builds (for Lethality). This tends to reduce their utility in the early game since they'll have a hard time finding spare points for Lockpicking. By the end game, though, they have enough cunning to unlock or disarm anything while needing only 1 point in lockpicking (or zero for the dagger/dagger cunning build).
The dagger/dagger dex build has two advantages that aren't reflected in the numbers. The first is a sky-high defense. Second is somewhat better ranged DPS via shortbows or xbows with the dex hotfix. The other builds are limited to using longbows if they want ranged damage.
And indeed CUN and daggers are the way to fly. Also some interesting stuff about lockpicking, how much you need for the hardest chests in this thread.
The lockpicking score is simple to compute:
L = (cunning - 10) + 10 * [lockpicking rank]
Your lockpicking rank is the number of points you have in the Deft Hands tree. If you have Deft Hands alone, your rank is 1; if you have Device Mastery, your rank is 4. As you can see, each point in the Deft Hands/lockpicking tree is worth 10 points of cunning. Notice that you can actually open locks without any points in the lockpicking tree if your cunning is high enough (I confirmed this in-game).
If you successfully pick a lock, you'll gain XP equal to D (with a minimum of 5). Thanks Sheffsteel for the observation.
Great! But how high does your lockpicking score have to be to pick every pickable lock in the game? Unfortunately I don't have the time or know-how to inspect every lock in the toolset to find a maximum value for D. However, there is a big hint in traps.xls, which contains a sheet called lock_difficulty with the following table:
1 Auto Success
10 Simple
20 Very Easy
30 Easy
40 Medium
50 Hard
60 Very Hard
10000 Impossible
So I would tentatively suggest that you need a lockpicking score of 60 to pick every lock that can be picked. You can achieve a lockpicking score of 60 by getting Device Mastery + 30 cunning, or Mech. Expertise + 40 cunning, etc. Of course, some locks will still require keys or event triggers to open.
Some people have finished the game with a lockpicking score of 60 and said this was enough to open everything. One person on the old forums said he was unable to open a chest with a lockpicking score of 64, but I don't know the circumstances. I would appreciate feedback from more people about whether 60 is enough for everything.
Respec mod is a rogues best friend! ;-)