they just use normal servos. the one with the saito flies with futaba 3003 (standard bushing servos) and the os guy flies with 3001 (standard bearing servos). both fly with mini servos for throttle but i'm not sure which ones.

i guess the plane will handle the 90 just fine just that it's a large lump coming out of the cowl. both my friends have theirs mounted sidewinder so they stick out just enough to make it look the part. the 56 saito in golden knight looks wonderful sticking out the side. the surpass with the black rocker cover looks good too. the 91 may just stick out a bit too much.

in terms of power, it should be great. i know both cubs fly really scale in the sense that they don't fly too fast and still have some difficulty with large loops. thier hammerhead/stall turns are usually not accompanied by long uplines. with a 90, you'll have more power all round.

as for me, i'm flying a cub .26 with a 30 surpass... enough power to make it a scale pleasure.