I just played Guild Wars yesterday, its pretty fun. I managed to build a little char, and it was fun. I trained skills with experience and that was fun too. I did see something cool which I thought, hey, thats a great idea, I should mention that on CB and see what everyone thinks of it.
They have a unlearn allowance. You can unlearn skills you have trained X number of times, this number is based on how much you have played, if you've played through 8 levels without unlearning anything, you've got about 24 points of unlearning available to you. Therefore you don't LOSE experience you've earned, but you simply have to be careful where you do put that experience.
Would something like this be a cool idea for CB? Instead of losing experience, especially during a change months, you have to earn the ability to unlearn your skills, so you can't just go around unlearning and training until you have no experience left. If you run out of unlearn points, and you can't advance any further (i.e. can't win fights in order to earn unlearn points) then you should retire your char, and start again. Simple as that.