To be honest, I haven't had a whole lot of success with rootless paphs. I've tried sphag & bag, sphag in plastic pots, sphag in clay pots, fine chc in plastic pots...
Rootless seedlings are the most difficult to revive, but if it's a mature plant, then maybe it has enough energy stores to send out new roots. I grow on the windowsill, and humidity is relatively low. Right now I'm keeping a couple rootless paphs in a small clay pot with sphag moss. The moss dries out every couple days, so if you do this you need to watch them closely. I don't know if it's any better than any other system. I didn't like sphag in plastic because they dried out very slowly, and I like that frequent watering helps bring air into the medium.
Good luck!