Both of mine are microchiped. Connor has been for 9 years and there has been no problems. I've heard about them coming out, whether it's true or not I don't know. I do have the vet scan him anytime he goes it just to make sure.
My dogs also wear tags. Connor has lost his collar twice in the last couple weeks. Not sure where it is at the moment. I'm sure it's outside somewhere, but we have 8.5 acres of woods. lol.