RE: YES!! just bought 4 star 40 kit, now need engine....
I have the 50SX in my 4* LOTS of fun. Clipped the wings one bay for even more fun, and it still mush-stalls and floats on landings. I would recommend, even if you build the wings full size, adding extra hinges 1 bay in from the wingtips so they can be ready for clipping in the future.
Scott