Originally Posted by GREG DOE

Whisky, Tough question? With the tank on the CG it's possible to move the airplane's CG further back. A more rearward CG will allow the airplane to turn with less elevator throw to accomplish the same turn radius, so the airplane doesn't slow down as much in the turn with the more rearward CG. The conventional CG location for an airplane with the tank behind the firewall might get too sensitive as the fuel burns off. The two pluses with bladder tanks is that you can set the needle valve much closer to peak RPM, and the tank can be located further from the engine.