As far as I have been lead to believe. The TRC-780 is made specifically for being a zone remote in a total control system and would use the mrx-10 to communicate to the total control system.
The MX-780 uses the same remote body but is an IR/RF remote for use in master remote situations to control say a home theater system and can use the standard URC bases but can be used with a MRX-1 for 2 way communication.
Both are programmed with a computer, bothlook the same appearance wise but differentiate in function
One thing I have learned in this industry. It is easier to pull a wire than it is to push one.
