This is SO much like Dungeon Master...

[Darklord]

I am sort of torn on the XP system -- I don't really like the thing where my characters can easily get out of sync, and I don't have the kind of control that I did in DM, with the four-class-at-once system.

There is kind of a solution to this,

SpoilerShow

Eventually you find an item which gives whoever wears it +25% XP. I used this to allow the characters who's XP was lagging behind to catch up.

Daniel.