RE: Flaperons for Edge 540??
I don't have the great wisdom you asked for but will give you my .02. With the proper CG you won't need flaps. The wing loading should be fairly light and most aerobatic planes will glide well. That being said think about setting up spoilerons. If you really want to wring that thing out they can help. A few examples would be Waterfalls, Elevators, Walls. All of these things can be performed better with some spoileron. I am doing some gross generalizing hear, but I would be concerned about flight more than landing. Notice I didn't mention Harriers. That is because some planes do better with flap and some do better with spoil.
David