I just looked at the Yak manual. If it says 130oz-in servos, I'd trust them on it. Does it have to be digital? Maybe, maybe not. Hitec has some good options either way:

http://www3.towerhobbies.com/cgi-bin...?&I=LXUZ89&P=0

http://www3.towerhobbies.com/cgi-bin...?&I=LXUZ80&P=0

Not surehow these compare in cost to the JR's.