Tom, you may have opened a can of worms here! The purpose of flaps is to increase lift to allow a slower landing speed. Period. Now on jets, it also has the benefit of increasing drag which allows the engine to maintain a higher thrust, and less throttle lag, which comes in handy should you need to go around, but this is not a factor with piston powered aircraft. Use of flaps won't change the inherent stability of your aircraft; it's just as stable (or unstable) with flaps as without. What happens that you naturally fly nearer the stall speed with flaps, so it may seem it's more unstable; which it can be in that part of the envelope, but it has nothing to do with the flaps themselves. Use of flaps can change your trim, and the faster you crank them out, the faster you notice the change. Best to go slow, and try different amounts of flaps. Depending on your wing loading you may find more or less flap works best for you. I fly a Topflite GS Mustang, and with full flaps it floats too much form my taste, and I usually only use about 1/2 flap to land. I also fly a Topflite GS Corsair that weighs 36# (!), and I can land it with anything from no to full flap. Of course there is a noticable difference on approach speed and the amount of roll out distance, but the point is I dont NEED the flaps, but the do look cool, expecially on a Corsair.