Unless you plan to replace the damaged AP tree I'd leave there to see how it progresses. My biggest problem with AP trees is that they too easily get Fire Blight damage here and can die from it within a few years even with controlled pruning.

On your 2nd point, giving a fruit tree 3-4-5 years to prove itself worthy is usually ample time. But that being said it took about 12 years for my 2 Bartlett pears to give me a bumper crop last year. With crazy weather patterns of late many fruit trees will bloom too early and get wiped out by a late freeze in April.

IME, the damaged pear will never produce properly as a real tree. I'd get rid of it and replant with something else.

I would echo gardengal's advice -- sounds like a dud. In terms of knowing when to rip something out, there are so many factors to consider -- watering and and other maintenance requirements, space, usefulness, etc. I have learned the hard way with almost everything I grow, I pull stuff every year, and my orchard and gardens are constantly evolving as a result.

I might pull the hit and run tree, and replace it with a healthier tree. I’ve had to do it with a couple of trees that were damaged in our yard by the previous owner’s dogs. I’ve replaced them, and it was a huge weight off to be able to move on with a healthier specimen instead of worrying over a tree that was never going to grow properly. I’m not sure about your other tree...I’d probably give that one more time and see what it does, as long as it’s not too difficult to care for.

If the plant was well established, you might graft a cutting from your favorite other pear trees onto that. Pears are fairly easy (high success rate) for grafts. Nothing like repurposing a good root system.