Hello,
I think its just a matter of what your looking for in a photographer. I know the reason alot of people like the idea of bringing in their own photographer, is because you get more bang for your buck (so to speak) For example, you'll get family/friend photos the day before your ceremony, then all day wedding coverage, and usually a TTD session the day after. Versus most local photographers, charge by hour, so most of the time you don't get as much, but that's not saying it still wouldn't work. How many people are you expecting?