Herman,
You can use what ever emitter that you want with the Mako. No need to change it out. I'm going to be using the impact emitter that i still have for mine. As far as the fire every three seconds that is going to be when your really going to want to test the IR. My Sherman would continue to fire but the IR itself won't go off until evey five seconds. That has more to do with the fact that the Mako is just a board used to give you compatability between the different systems. when you start your test you'll find that even if the tank itself fires every three seconds that the IR does not.

It might be easier to use the tamiya one since you don't have to worry about placing the right wires in the system but it isn't required The Mako will just send a "fire" signal to the IR ports that are on the board.

Bill