Personally; I find the extra switch just one more thing to worry about when I'm concentrating on my AC.

If you must use flaps I'd suggest the 3 position switch- it's quick and easy - no guessing when you are looking at your AC and fiddling with a knob that you cannot see.

I have two planes with flaps - P51D and a S Chipmunk - after the first few fights - I have no use for the flaps. The planes take off and land perfectly without them.

Other than scale appearance - I have no use for Flaps.

IMHO