You'll find a lot more beatles covers played in pubs any night of the week than mozart covers.
Need the right hardwareand/or the right coniguration of the software, it sounds like.
I've got a fatality platinum (the input is just too handy, and the price was right) and have no noticeable latency whatsoever; it's good enough to play live with other musicians.
The default settings were completely inadequate and my latency was terrible, but a little googling showed me where i was going wrong and now i'm pretty happy.
only gotcha is ive got vista x64 (4GB ram, still have free slots) and there's STILL not drivers for the Kontrol (I bought the HW version) after more than a year of promises from NI.
It's still fine to use the software side, I just get no floor unit to interact with my presets (bummer).
So there's my only complaint - Native Instruments completely inadequate development cycle/support.