LC:

Multiple servo use has a couple justifications. Sufficient power is only one. Others include the flex of the control surface, the possibility of ripping the control horn off under high aerodynamic loads, (two horns are stronger than one) and of course, the old standard, redundancy. One fails, the other will help you get it home.

Friend of mine had his 60 stick out weekend before last, said it felt funny in roll. Right. When he brought it in we found his right aileron servo was dead. This was, of course, only one servo per aileron but the redundancy got him home with an uncrashed airplane.

Single heavy servo is OK up to about 100" span, but I personally use four wing servos at 80" and larger.

Have fun.

Two servos or four,
. Build a twin, it'll roar.

Bill.