I realize this is an old thread, but I'm wondering what you ended up doing?
I've used XLD to rip CDs to my iTunes library, to transfer my ALAC to my X5, and, for some reason, I once got it into my head that I wanted to stop using iTunes altogether and batch converted the entire library to FLAC. Of course, I failed to save my old library of ALAC and ended up reconverting the whole thing back.

There was a fair amount of tracks that were corrupted and lost when I did the reconversion, though, and a lot of albums lost their album art or were assigned the wrong art.

I think this was probably user error (to some extent), but if you go this route (if you haven't done the whole thing already) be careful what settings you use.
If you do use XLD, the destination path and settings should be as outlined in this thread:
http://www.hydrogenaud.io/forums/index.php?showtopic=104178 At least that's what I found works for me.
I would also recommend splitting it up into several smaller batches so it's easier to spot anyplace things may have gone wrong.