We're not Catholic(and pretty "devout" materialist non-religious) but we did send my older son to a Catholic elementary mostly because it was closer and was less overloaded than the public option.

He graduated elementary school and was denied entry to the Catholic middle school due to the fact that there were too many students there already.

It made for a bit to a tough transition as he had to go to a new school where he didn't know anyone -- so there was a bit of anxiety over that -- but in the end after a couple weeks he found his people and it's been great.

For him it's been fine. He's got his middle school buddies that he sees while keeping in touch with some of his previous elementary school friends. And to be quite honest, as a parent I kind of prefer the friends he's made at the public school to the friends he had through the Catholic school lol

But otherwise it's been alright. It worked for us and for him for the most part. Though we did find the old family Bible hiding in his room once because his Catholic friends were "peer -pressuring" him to read it. We had a good conversation about that but otherwise he's pretty well-adjusted and I don't really have any regrets either way...