I would probably hold onto him, although Hundley has been a machine. He gets all the PT in SD. Guy who has Mauer in my league just picked up Wieters, though. There are a few other solid catchers on the FA in my league, but this guy (who is a solid player) went with Wieters.
That said, I would probably just hang onto Wieters, he will be fine. Its up to you though, you wont be losing much if you decide to jump ship.