I don't know a lot about pear compatibility and I don't make many pear trees.
I have a list of pears which are compatible with Old Home and those that are
compatible with Quince and when I doubt, I usually put the unknown pear on
Quince
with an Old Home interstem.
Three years ago, I received a request to propagate an unknown European pear
(tree
about 100 years old and wood was weak, but acceptable) and I just can't make
it
grow on either Quince-OH or Quince alone. It hasn't died, but the growth is a
measly three inches/year.
Last year I got a request to propagate another unknown pear (60 year old tree
in
good health) and it seems to be failing on both Q-OH and on Quince alone. It
also
didn't take on Asian Pear (20th Century).