kmonster - Good points. They get a lot of resistances, AC, MR, missiles, poison, disease, charm, slow, saving throws, non-magic weapons... I need to consider them further. They may be better for killing mages than the Wizard Slayer even...
anamorphic - For each player it is different, I feel I have to justify a character's presence in my party. As a fighter I can see the worth of a monk, but they mostly serve this one role. Can't heal my party, cast mage spells or do much thief stuff. Now if it was an NPC, that'd be a different story.
Tallima - I'm never overly worried about cash in the game, I always include a very active thief in my group. I would love to seem them tweaked even just a little, to make them more worthwhile. Even something as small as allowing their Lay on Hands to heal others would be pretty cool.