I have a buddy that did this to his Nextstar. The plane is setup already to have seperate aileron servos used with a center flap servo for both flaps. I have flown this plane both ways. I am a instructor for my club and the plane flys great either way, but the flaps allow the plane to land much slower and a lot more stable, but allows the speed to be gained in level straight flight without the plane climbing. It is a trainer, so it will not come in wide open anyway. The removal airbrakes IMO make the plane climb too much while learning or teaching in my case.

The mod is worth the time if you plan on doing it. It will make the take off distance shorter and landings more stable. In higher wind (windy days), I would not use them (flaps) as they will slow the plane too much while landing into the wind. Land normally on windy days, unless it is a cross wind, but then you may not want to use them that way also. Depends on the day.

My buddy only has three servos in the wings joining the flap control rods together to make them move together. Make sure the middle (flap) servo has enough clearance and will not touch the rear bolt holder or the balsa itself. May have to trim the balsa some to allow for clearance of the arms and rods.

Hope this helps