As mentioned, be careful. An example is the 4 channel may come with 422 servos and the flight pack may come with 425BB's. Big difference.

Multi-memory or multi TX's. You still have to be careful. Check for the proper model memory slot and fly your model safely, but if you flip on the wrong TX brought to the field, you may shoot me down! We need to check all the little details all the time or we get into trouble! Isn't this fun?