I get about 5mph stall decrease with flaps and so it's worth it if you really want to land slow. (Rollout varies with the square of touchdown speed.) You do loose a lot of aileron authority, though, so that's a consideration. Gap sealing the elevator makes a noticeable difference in authority. I did Lowell's clear tape thing. Use the heavy duty packing tape and it lasts a long time. (More than two years on this last set.)