I'm going to go out on a limb and make another comment in this thread
My rogue has moved on the 10s, and the stealth experience is much better because careless use of it, such as moving in the open around many monsters, not peeking around corners etc. will cause him to be spotted. His limited attack powers mean that he can't fight large groups. Suddenly all those things such as noise levels and search times make a big difference, and the experience is superb.
If this was the desired experience (and I hope it was) then I agree with the original design that he shouldn't have area attack powers. He seems to be designed not to be able to take on massive crowds, preferring to avoid them or take them out one by one. If he's given an area power, it should be expensive and slow so he can't overuse it.
I'm not even sure he should get XP credit for sleight of hand. It's really cool peeking around corners, using it on a boss's goons so they whittle his health down, then going in for the kill. Sleight of hand seems built to make your life as a rogue easier and I'm ok with not getting experience for kills I didn't carry out. I'm also ok with getting little fighting XP since the rogue completes quests faster.
Of course the usual disclaimers apply -- feel free to tell me I'm completely wrong about this, especially at the higher levels.