I've been running some published adventures in D&D 3.5 and two of the PCs in the party have contracted lycanthropy (they're now were-rats). They've had their first night of the full-moon. While they're not so happy about losing control of themselves and attacking their fellow party members, they absolutely love the bonuses they get.
I try to be a very permissive and generous DM, so I'm okay with them remaining were-rats and finding a way to control their lycanthropy.
That said, I'm also very precise about XP awards (different based on the level of the PC, etc.). So I'm going to respect the rules about the animal HD and the level adjustment.
So, what do the rules say about the PC's XP and when they will level up, etc., if they don't get cured? Also, what published options, feats, spells, variants, etc. might make this less onerous on the PCs?
Addendum: is the variant rule for reducing level adjustments at all a good or balanced option?