Using flaperons......need help
I think in the case of those Fun-Fly models, the wing is so wide (thereby putting the flaps farther back than a regular plane) that they tend to act a little like elevators, and will make the plane pitch down at higher speeds. I have flaps on my Ultra Sport 40, and regardless of what speed I'm flying, it NEVER pitches down. So, I think a lot of it has to do with the design of the plane itself, and that all planes will act differently.
But I will say this... Put the flaps on! I just love a plane that can slow down to a crawl on landings. With my US40, with full flaps, you can jog next to it and keep up with it! It is a sight to behold!