I do get a breakin taste with rayon in my kayfuns. I got use to it knowing its going away after a few hits. IMO I'm getting the breakin taste from having my wicking pretty tight in the coil along with not letting it sit long enough to fully absorb the juice but I've had no dryhits, leaking or wicking problems wicking my kayfuns my way. The rayon doesn't expand when juiced so you have to make up for that by wicking it quite tight. Once you get rayon wicking down in whatever atty, you'll not go back to any other wicking material.
Yep - rayon and I didn't get along in the beginning. For a week or so I tried various builds w/ rayon and wasn't getting it right. So I just went back to KGD. Then a few weeks later I gave it another try - got it right and now use rayon in all my builds except the soft NI200 coils.