One thing to keep in mind, too much elevator (relative) on a nose heavy plane will cause a snap at certain speeds, at certain speeds of elevator input, and in dives. The thing to remember is it doesn't depend on the way you set your balance point in the CGrange to fit your flying styleit all comes down to how your plane is balanced vs wing loading, and how your throws are set.

Couple cases in point. I have a King Kobra and an Edge 540 that both exhibited the same characteristic. Both very different airplanes, both did the same thing. Now, on the Edge, there was little Icould do because I had an engine on there that was WAY bigger than spec'd (a 1.08 on a .60 size bird). Even though I'd balanced the plane "tail heavy" for 3D, the wing saw the plane as too heavy overall for the spec'd wing loading. Now, I could pop into a wall with this plane really well, but if Iwas too fast on the elevator, it would snap to one side. Iadded a tad of expo, and the snapping thing diminished a whole lot.

On the King Kobra, I had the "correct" sized engine, but balanced the plane "nose heavy" to kinda cheat in certain maneuvers. Again, if I yanked on the elveator too fast, especially in loops, the plane would snap. I got tired of this snapping and didn't want to cheat anymore, manned up, balanced the plane neutral and learned how to do those certain maneuvers the proper way. After taking the extra weight off the firewall, guess what happened? The snapping disappeared on low rates. Now Istill kept my high rates the same, so of course in high rates the snapping was still there if I got on the elevator too fast, BUT, it dramatically decreased. The plane was way more stable and actually more fun to fly.

Now I'm not saying you have your plane balanced wrong, not at all. Just another thing to consider. When an airplane get too heavy for it's specified wing loading, "funny" things start to happen, usually snapping types of things. Also don't forget P Factorwhich basically means that when the prop "disc" angles away from the main line of travel, the downward swinging blade has more pull. Depending on your throttle input and power plant (including prop size), this could mean that your right wing would speed up and get more lift, OR, it could actually mean the down swingin blade has more bite and slows down adding to the torque phenom. And it doesn't take much variance for either to happen. Example, Knife Edge Coupling, which is more evident on certain kinds of planes and/or setups.