As much as I would like to see this, I can see it being abused.
(snip)
Personally I like the idea (there are some combos I'd like to try), but it will never be implemented for a hundred different reasons we can all come up with and honestly shouldn't be.
Meet halfway? Right now there is nothing retained. Getting to top after losing that much XP is very hard. You are discussing how one can adjust on the fly, which implies full retention. How about imposing a penalty, substantial enough to prevent people from doing it all the time, yet not as crippling as it is now with 100% loss?
I am more worried about people jumping on every FOTM that comes along. I don't want repeat of scouts or nothing, or P/S fiasco. So, letting people retain some XP so they can switch from a class combo they don't like or one that is nerfed; yet not so much that they can do it all the time - that makes sense to me.
I am more than willing to concede something, provided like you said, the penalty is stiff enough to keep people from swapping at will. I'm not quite sure right now what we could come up with that would make it fair to everyone.
Maybe something like for each level you lost you get a xp% increase on kills? Or maybe even quest turn ins? At level 82 that would equate to 82% bonus xp from turning in quests. This would have to be controlled somehow though, maybe each time you leveled you lost a little % of that bonus. I think 82% at level 82 would be way to high, but 82% at level 1 wouldn't really do any good either. How about a temp buff, maybe 2-3 hours each day that would give the % on turn ins only, going away once you hit the level of the class dropped.
Example:
If you are 82/50 and drop the 50, you would become 82/1 with a 3 hour buff that granted 50% bonus xp on turn ins. Each level gained would reduce the bonus % by 1 percent, until you are 82/50 again, at that point the buff would no longer be available. This would give you something in return, while helping you get back to the levels you were previously without making it too overpowered.
We could go another route and combine ideas with Cike. Let the FOF reopen the zones up to the level of the dropped class, but also giving a 1 hour 25% bonus xp turn in on quests.