Actually the 700R is the same size as a T350. The 400 has a large case diameter. The 400 will take a lickin and keep on tickin but the down side if any is that it is a resource hawg. It takes more torque to use a T400 that a T350. Most of the time it is not noticeable, and we are probably talking about .001s of a second on the 1320. So not anything that most of us are going to be too worried about.