ORIGINAL: Rodney
Contrary to what has been said above, I have often trimmed out my big bipes to fly hands off in level flight whether upright or inverted at one throttle position (usually about half or two/thirds throttle). Now, if I change throttle position, trim will slightly change. I have also trimmed out several monoplanes (.40 and .60 size) to do the same thing. It is difficult sometimes, you have to play with both the CG position and usually have a little bit of up trim in both ailerons when the aileron stick is centered, especially on the monoplanes.
Upright and inverted flight are not the problem for "Hands Off" flight. Knife edge is, and it will not be "Hands Off" in pitch and possibly roll, when the model is trimmed as you describe. Trimming a modern pattern model to be neutral in pitch for upright and inverted flight, is a fairly trivial matter, and over a rather wide power/speed band. Our wing loading is low enough to allow that
Current top schedules particularly in F3A, demand a great deal of pilot attention.....it's easier on the pilot if he minimizes his workload with an optimally trimmed model for "hands off" knife edge flight. This requires a forward CG and BTW, spinning and snapping the model with precision will become easer. All other flight regimes will fall in place once that's achieved. Unless the model is so badly designed that it simply isn't capable of doing certain maneuvers.
To the original poster, we must compromise when trimming the model to achieve the best flight envelope the model has. And BTW, I abhor e-mixes, try very hard not to use them