i have several 6400 bricks, and 1 champ brick too.
when testing several motors i decided to try both.
to my surprise, the figures were very different.
the motors tested were the 8.5's, (called by the color of the end bell) used in the champ (clear), the 1s in the 4site/p51 (black), and there are 2 from helicopters (the grey from the solo pro, and the white from the bravo sx), and 1 from the 9 eagles planes (p47) that uses same motor as the bravo, with its own gear box-same # of tooth.
i used a 5.1" horizon prop and a hyperion 240 cell, and the original gear box.
figures are thrust/volts/amps/watts/rpm
clear: with champ brick: 40/3.73/1.5/4/5880
with 6400 brick: 40/3.73/1.2/4/6360;
black: with champ: 45/3.60/1.5/5/6480;
with 6400 brick: 55/3.73/1.8/6/7080;
grey: with champ: 45/3.80/1.4/5/6240;
with 6400: 55/3.62/1.8/6/6870;
white: with champ: 45/3.78/1.6/6/6600;
with 6400: 55/3.72/1.8/6/6870;
this 1 with its gb and prop (similar to hh 5.1):
p47: with champ: 50/3.76/1.6/6/6600;
with 6400: 55/3.64/1.9/6/7110
i was expecting both to be the same but it's obvious that there are electronic differences in design/manufacture and/or programming, and the champ is markedly milder, so it's not just the motor that makes it less powerful.