What algs would you use to do this? Are there any that will just affect 2 centers and nothing else? I don't know any algorithms like that - when I need to swap two pieces, I do a 3-cycle commutator including another piece of the same color as one of the others.
If I recall correctly Derrick Eide used a similar method for 4x4x4 BLD; he had some complex algorithm for swapping two centers, although I think it might have swapped two corners as well, and he just swapped the corners back and forth until he was done. But I might not be remembering that correctly. He was able to go sub-15 with it, but that's just because he's very fast - the problem with a method like that is that it's a LOT of moves; it's unlikely you could get world-class times with a method like that.