Has anyone gone from having a loose pipe on their horn to a screw in?

Notice any playing differences after the surgery?

Yes. Kind of hard to do an immediate a/b since it takes time to get a pipe removed and install collar. Although I have used press fit pipes on horns with a collar, picked the one I like best, and had that a threaded ring soldered to it. If there is a difference, it was much too subtle for me to pick up on.

The key difference for me was not being annoyed every time I removed the mouthpiece!

Yup, no real sound or feel differences, just the practical.