RE: Flaperons on an Avistar
Nothing wrong with trying the flaperons, but I too wonder about the effectiveness on a trainer, even an Avistar. It may land a bit faster than flat bottom wing trainers, but I doubt that it's substantially faster.
Remember too, that flaperons will likely cause a change in pitch when applied, which will mean having to "get on the elevator" when deploying them, or trying to mix some elevator with the flaps. What I'm saying here is that most beginners have their hands full just trying to learn the basics, without having to deal with bells and whistles.
However, adding the flaperon capability now does not mean you have to use them now. You could leave the function disabled until you've learned the basics, then kick it in later on.
Whatever you decide, have fun!
Oh, and I'd place the servos side by side. As ,ong as the angle isn't really severe, it shouldn't be an issue.
Dennis-