How about one +12 and 3 grounds? since the MR16 board switchs ground it would be better.
But yes it would work fine. I am going to do the same but my cannons will have 3 of each color on them and the same colors will hook together at the canon and feed 4 conductor. The four conductor can run a lot of mr16's on it.
Then back at the controller the first canons red will hook to channel #1 neg terminal, green channel #2 neg terminal, blue channel #3 neg terminal. Then cannon #2 will hook reds to ch #4 , etc, etc,
but since the pcb has spade terminals I am just going to put them on the end that hooks to the controller and so I want use the plug.
Just thought I would let you in on what I have in mind for it.
RJ