I'd like to hear more opinions on wether or not higher voltage feels smoother, that is a big part of the reson for wanting this setup. I already have an M.M. running in the car. 2 or 3s M.M. and 400 size motor would be almost as light as 25 (with heat sink, ubec, and equal watt/hr 5s) and really safe and easy.
My only real experience between voltages has been 2s and 3s with a 4100, 6800, 8000 in an 18t. Lower kv motors seem smoother and higher voltage seems crisper. Maybe the 2s bat. was just a little weak for the higher kv or taller gearing, want others opinions.