Just sharing what info I see.
I just realized, another way to look at it, is if one wants to be slightly safe, but want more cuttings, one can air layer a vine first, then when the vine is rooted, you plant the vine, wait a bit then you can do a cutting on it. Hopefully the air layered one will continue to grow healthy even if a cutting was taken form it. So hopefully you get 3 plants, the original, the air layered and the new cutting.
Still yet to try airlayering but soon.
TTFN
Arvin