I've used flaperons, on two planes. One was a 'stik' type and the other a 'pattern' type. Not that impressed with them. Fun to play with, but, that's about it.

I'd agree that up to about 10-15 deg (depending on airfoil and wing shape) they work to modify the airfoil to give more lift by changing the camber of the airfoil, but, they also effectively change the incidence of the wing. This is similar to the 'take off' flap setting on many airplanes. There is a little bit of drag penalty due to the increased lift. That's where they can be like a flap for landing. A bit of increased lift (lower stall speed) and more drag (slows the airplane allowing a steeper descent).

At more deflection you are running into a situation where you probably have airflow separation over the control surface (at least that's what it seems like when flying). This is where things go bad in a hurry. You end up with big drag brakes on both wings and little aileron control. The airplane will come down in a hurry, and, if you aren't on top if it with the rudder, it will probably turn turtle on you (yes, been there, done that).

All of this is for 'normal' flight, where the wing is actually doing something, not 3D type stuff, which is a whole other category. In those cases flaperons can be great tools (as stated above somewhere) for maneuvers as well as descents/landings.

As for spoilerons, I've never tried them. I've been meaning to, just never got around to it. If what you want to do is come down faster, they are a way to go.

The best bet, if you have full length ailerons already, is to split them and have the inboard sections work as flaps. I've done that on two planes and it works VERY well. Turned a real 'floaty' plane into one that was pleasant to land.

charlie