I fly just two DS821 JR/Spektrum servos on my four ailerons on my 1/5 scale Cox Pica Waco and they work perfectly. I am overpowered with a 1.6 class electric motor and 20x12 prop.
I think any 4 basic standard servos of decent quailty will be more than enough for this model, even if it is overpowered.
Actually, I think GP loses some scale points for leaving off the aileron interconnects and going to 4 aileron servos. If I sell off my Cox/Pica and get the new GP Waco, I will likely go to two aileron servos and the interconnects. This is not a Monster Pitts or an Ultimate biplane...
