Long time since I even had Velo XFade enabled for a solo instrument....
I hadn't realized it jumps between layers, instead of fading, when VelX is disabled. Now I hear that it jumps instead of fading when VelX is off.
Many sampled instruments have a sudden difference between a given velocity on note-on and the next, I can't let that bug me. I would rather deal with CC expression to smooth that out than have that phasing, which just sounds awful to me. Now, I'll expose the instruments and as an M.O. I write linearly/contrapuntally with monophonic instruments often so I don't really go for masking this sort of thing in the first place.