The number I was quoted for stability was 27%... not 25. (25 being easier to calculate... its normally used for the model's pivot line.. as it ensures a margin of stability.)

I agree that being back at 30% is a bad idea in general. You may have trouble getting a stable trim setting for level flight with the small, slow aircraft. If that pivot line is changeable... I'd change it.

The slow speed airplane... you're torque required is going to be VERY small if the pivot line is very close to 25%. The larger factor to worry about will be the "hanger rash" forces put on the servo. Witht he 30% line... you need twice the power as if the pivot line was ahead of the neutral force line the same amount. (you're on the edge of the power range of the 27 in-oz HS-81 in my opinion.) Move that pivot line... and I'd be comfortable putting a Tower TS-5 in it. (appx 12 in-oz... about 1/3 the weight of the HS-81 and slightly under half its power.)

Note... the flying stab is not necessarilly the best choice for maximum maneuverability at low speed. Deflection above appx 18 deg... you can stall the stab. You get MORE control authority from the same size (total area) 50% fixed, 50% moving stab/elevator setup at low airspeeds.. and you'll probably never fully lose control authority of the stab (before the main wing stalls) with 30 deg deflection on the elevator.

Flying stabs are virtually essential for tran-sonic and supersonic flight. They are GREAT for precision trimming with minimal drag. (why the speed design I flew used it... minimal drag.) They are rotton for aerobatics at low speed.