The weight of the servos in the tail is the key.... 5645's are pretty heavy servos, about 2.25 oz. each. They do put out over 160 oz. in. of torque at 6 volts, but for a plane this size, you really don't need that heavy and powerful servo on the elevators. They would be great for the rudder and ailerons, since both those surfaces are so big and prone to flutter under 3D loading. If you are worried about being tail heavy, then you may want to opt for a couple of 1.5-1.6 oz. servos in the tail for the elevators, like I stated above in this thread, I went the cheap route and used 3010's and 3305's with no problem and no balance problems with the lightweight FX.91 on a bisson muffler. The airplane came out very light and flew extremely well. I can't believe folks are putting ST2300's, FX160's and the like on this airplane, then cry when they blow the tail feathers or wings off. Mine worked great with an APC 14X6 prop. Of course, we are only about 800 feet above sea level here.

This airplane does not need a real big battery pack either. Try a 2100 NiMH 6 Volt (4oz.) AA pack from MPI. I was getting over 5 hard long flights out of mine, before quick charging with a smart Charger. If you quick charge between flights, it will almost be topped off by the time you refuel and discuss the flight for a few minutes with you buds.

Good luck with your plane. My only problem with mine was the inadequate strength of the landing gear on harrier landings, it is soft and short.