RE: e-flite mini edge 540
This plane flys best with the cg near the back of the range provided, 60mm is a good start. I found it flew badly at the front of the range, it snapped out of loops. I moved the cg back and it was a totally different plane.
Ditch the E-flight gearbox and get a Cobri. It's the last gear box you ever buy. They are quiet, super strong, and will give you the confidence to really fly the hell out of this plane.
It's a great plane, becoming my favorite out of 7 others.