There is no perfect CG for everybody. Even with what I posted above, it usually take me numberous flights in order to get my airplane trimmed and CG'd the way I like it. I continually move the CG aft until the airplane gets very pitch sensitive and then move it slightly forward from there. That is why I agree with the guys above, to not waste any money on a CG machine and just use your fingers under the wing or at the wing-tip to get the CG set within the acceptable limits and then fly/adjust as required for your flying style. Once my CG is adjusted for my flying style I couldn't care less where it is, just how the airplane flies.

Most airplanes do not have constant cord wings. Example: Extra 300, Edge-540, Cap-232, SuKhoi Su-26, Yak-54.