The 4* is not hard to fly at all. If you are able to take off and land well with the nexstar and and are in full control of it while flying (not the plane flying you) then you should have no problems moving to the 4*. Just move the radio gear from the nextar to the 4* and you'll be ready to go

Make sure you do some taxi runs first to get used to having to add a little right rudder on the takeoff run (necessary with all tail draggers).