got some great advice so far. I have buit three 4*60's. really great, easy building kit. The last one I kit bashed into a 3D version. I split the ailerons and built them up (instead of solid) to twice their size. I extended the elevators and rudder the same way, buy building them up and counter-balancing them. I also knocked one degree of dihedral out of the wing. Not quite flat, but not the extreme the dihedral brace used with the kit. I used a 1.20 four stroke on it, with some very heavy duty servos on the ailerons, dual elevator servos and HD on the rudder using Pull-pull. It rocked. Several friends at the field are flying the ARF with OS .91FX's. Like the one gent up top said, many of the .90's weigh the same as their .61 counterpart. You can always throttle down and exercise throttle management, but you can't get more power when you want it, unless you already have it mounted up front. The airplane is a real floater, if it's moving, it's flying, so plane on spoilers or airbrakes is you want to spot land, other wise, they just don't seem to want to come down, like a glider.
Plan on some mixing in your computer radio, because these plane, stock, have some real coupling issues. They are very neutral, but require rudder to aileron mixing for rolls and elevator to rudder mix for knife edge. Have fun, they fly great and are pretty tough planes.