I think my 'roster math' was off. As Rob Antony said, there are really five players fighting for two roster spots (Butera, Towles, Burroughs, Florimon and Revere). And if we assume Revere is on the roster, there are four people for one roster spot. Parmelee's a given. Means that it's the 3rd catcher or Burroughs, and if it means Doumit is in the lineup more, I'd go with the third catcher. I do like the flexibility of so many players.
I too like Doumit's veteran persence, but I don't think a reduced role for him is a terrible idea. He may be more injury prone than anyone on the team and that's saying a lot. He could fill Thome's late inning pinch hitting role well with the added bonus of being able to catch day games.