I have my flap set on a 3 position switch for my Boomerang intro. I find that having 30% flap for take gives a very nice and smooth lift off in 30/40 meters. As for landing i use maximum throw (about 85 deg) on flap and when i flip it into position give simultanuously asome down stick to compensate, and you can hardly see the plane changing altitude, i just make oneround with full flaps out and come in for a very slow and rock solid landing on our rather short runway.
Applying brakes (just for fun) would make the boomerang stop in less then 50/60 meters.

Regards.