Just went to post this today, but I'll tag on here.
Club I want to play has NXS1, but most of my tracks are in FLAC.
Using external software to convert them is fine, HOWEVER, you then lose all your analysis, cue points, beat grids etc - and this isn't really acceptable.
If you look back in forum threads, the argument was always "not enough demand" / "use wav" - however that was then - and the fact that the NXS2 range support FLAC/ALAC - means people will be using it - and (like me) they will then be pretty miffed when they can't use those files on anything else.
As they are lossless compression techniques, doing a conversation will make no change to the audio data at all, and also won't require trans-coding (just decompression) - so will be really fast.
I think this is pretty important now - especially as there is currently no other solution than "convert them yourself, then re-enter all the beat grid cue point information"...