Clark,
First Asians that I bought came on P.ussuriensis (Harbin pear). Two(Chojuro & Niitaka) are still here, and going strong at ~ 20 years. Shinko was taken out when my wife put in a tennis court. The other one was Korean Giant, which was a FB cripple, and finally died back to the rootstock - but the rootstock kept suckering, so I moved it; think it's still throwing out some suckers, but never has regained enough stature to graft anything onto it; maybe I ought cut it to the ground and stool it - but I have so many volunteer calleries popping up all over the place that it's hard to think about expending any effort...

In the meantime, I've used OHxF 513, which is reputed to be compatible with Euro & Asian pears - without issues associated with 'pear decline' of Asians on some understocks.
Have also stuck an 8-10" piece of 513 on callery as an interstem between the callery and fruiting selection. Those trees are still in a nursery row - and would be tough to dig and move now. Noticed a couple of them just the other day - approaching 15 ft tall - not sure the 513(semi-dwarfing) has exerted any dwarfing effect whatsoever, though...

Thanks lucky_p I guess if nothing else we can't beat the price of callery right? Lawyers nursery has some great deals on rootstocks in the price range and quantity I'm after right now but for obvious reasons does not offer callery. My goal like everyone else is to get some trees in place that I won't need to worry about doing more than routine spraying for the next 30 years.