Just a note on the Krymsk rootstocks - I've had fairly poor luck with
viruses on them, I believe. Most seem to take fine, but I lost the
majority of the Krymsk-5 cherry grafts in 2010 and also the Krymsk-1
plum and apricot grafts this year (lost the whole plant, not just the
graft). Might be worthwhile to order certified virus free scionwood if
you'll be experimenting with these.