Also, just thinking out loud here, could you maybe remechanic your character, but keep the fluff? For example, say you were a shaman in 4th Ed, and don't like how the class works. Could you remake your character as a warlord (or cleric, or artificer, or whatever) and explain the change away in your game world?
Personally? No, I couldn't do this. I don't really separate between crunch and fluff. To me, they're part of an organic whole that forms the character, each bit as integral as the other.
That and part of the problem in my instance is that the characters just aren't performing their role in a satisfying way. The first one I had, for instance, was all about manipulating the battlefield by moving PC's around it. It could be good but it really required a LOT of inter-party meta-gaming to be anything above average. And then the second one required a lot of timing on my part because 90% of it's powers were interrupts or immediate reactions which just annoyed everyone at the game and weren't very effective. Neither of the characters were doing their job of leader very well, and so for me at least, neither were very satisfying.