Here is a thread that discusses fireblight resistance in apples but the principles in pears are the same.
There was an NC-140 apple trial that had Gala on M9 and Gala on B9. Gala is susceptible to fireblight. The orchard was hit pretty heavy with a fireblight outbreak. Most of trees on M9 died or were heavily damaged. The B9 trees largely survived with little damage. The trial is online. I don’t know of a similar trial for pears but i suspect one exists.