Yeah,
Don't forget mameox/mamedox is still based on the MAME 0.84 core, so the games that don't run in .84 won't run in mameox.
I'm considering removing the drivers for all the 'unplayable' games in mamedox, and games that the xbox just cannot handle. I realise MAME is all about 'documenting' arcade hardware/roms (or so they say

) but for me, xbox mame is all about playability. so if you can't play it, why support it?.