Yeah, I think it would turn me off. One of the things I really like about 4E is the tactical aspect of the battles. Similarly, I really prefer the encounter portion of pbp better than the roleplay between battles. I struggle to maintain character in such stilted context. Losing out on the decisions as the battle progresses would probably make the game much less enjoyable for me.
which I've shamelessly borrowed your method of all the bad guys then all the PC's to keep it moving.