RE: less power from 400 motor, 30 esc, 10 cell combo
The reason the voltage is higher with the stock 400 is because it is not putting as much load on the battery. Your Permax is a much "hotter" motor, meaning it is wound to spin faster than the stock 400 on a given voltage.
Are you running the same size prop on the Permax as you were on the stock 400? I ask because the voltages you measured for the Permax are alarmingly low. You're putting way too much load on those batteries, which indicates to me that you're running too large of a propeller.