I co-own all three of my GSDs. They all live with me, and are MY dogs. I also co-own Russell's litter sister, but she is my breeder's dog and lives with her.
However, they spend a good deal of time at their breeder's house. Either just an afternoon of us visiting, staying while I go out of town, someone staying out there for a week here and there to exercise for a show, or Russell camped out there because one of the girls is in heat. She only lives about 45 minutes from my house, so it's super convenient. Sometimes she'll call me up and say bring the dogs out and hang out.
We show our dogs too. I pay for entry fees and handler fees on my dogs, but we share hotel and driving expenses if we go to a show together.
I think it all depends on what kind of relationship you have with your breeder. Mine has become one of my best friends.
That sounds like an amazing relationship you have. Really great!