Isn't serato drifting with chirps etc? Because if i chirpscratch on djdecks/finalscratch records the starting point of the sample slide's away, it's very little diffrence but enough to fuck up your chirp.
I really havent had much problems, even with some of my fastest scratches. My only probs have been when running the searto program as well as my other music software, But thats just down to comp speed. I havent noticed drifting, but then Im also not the best scratch dj.