You are planning on using Futaba 9202 servos in the GS Edge 540? This is a standard servo that is coreless. These are the servos that you should be putting in the 40-size Edge profile on a 6V NiMH batt. pack to get decent response rate out of those 9202s. That is what I have in my Hard Bet Mk III, which is a 40-size Fun Fly. I would suggest that if you are conserving funds, go with the Hitec 605 / 625 on ailerons and elevator and the Hitec 615 / 645 (the second number is the newer version) on the rudder. Then go with a 6V batt. pack (NiMH to keep the weight down).
Just my opinion.
Kevin