RE: Question...
The 10C whether or not it has a module on it is a much-faster transmitter than your 8U, due to the new and much-higher-speed processor in it. It also has easier programming and a few more features.
The 10C with module can accept the same transmitter modules as your 8U, and still be used with the 2.4 GHz FASST system. If you purchase the 10CG, which has no separate module, then you are limited to the 2.4 GHz FASST system, only.