We have 800 trees approximately now. Not all are producing yet, since some are very young, and many varieties will never produce much. I planted a lot of heirloom varieties for historical preservation, not necessarily maximum yield.
Yield is a funny thing. Our very most productive tree is the Kieffer pear. Even though the trees are still young, they gave me 300+ lbs of fruit each this year. Unfortunately, it's my least favorite pear flavor.