Pete,
Don't worry about the Jr. 3421 servo's. I have them in my CT-114 and they are plenty. If you are worried about that. Reg. your voltage up a bit. Folks in this hobby tend to over Eng. in this and other areas and the big 3d machines caused that mode of thinking. With sealed surfaces and less throws on these jets you just don't need 3d power. It least not on the smaller to Mid birds. Like KC said just keep your arms short for more torque.