I used JR 821 (Spectrum) digitalservos in a 2M Pattern plane and flew it from Sportsman through to F3A class . . I was super impressed with them for the money. Great servo, OK power, OK speed, good centering, and good life. They are only single ball-race on the output, but they stayed reasonably tight.

I have no trouble recommending them for sport/competition flying in planes up to about 74" span and 12lbs . . BUT not this size if it's a 3D design. Need more torgue and Metal gears for that.

Cheers, JB