Aft CG is going to give you tighter radius turn and the need for less elevater to maintain control, but, will make it more sensitive and pitch stability.

The reason you'll get tighter turns is because the elevater is producing less down force, or negative lift. This downforce ultimately detracts from the lift created by the wing, the more lift you generate (pos' and neg'), the more drag you create. Unstable military jets can have such an aft CG position that the elevater is actually producing positive lift, only because computers are doing the humanly impossible job of maintaining pitch stability.

Swept wing aircraft can have unusual characteristics in high speed/high G turns where the tips (behind the CG) stall first but the roots (forward of CG) remain in flight. This effectively moves the centre of pressure forward of the CG (same effect as moving the CG too far back) and the aircraft becomes pitch unstable, usually resulting in an uncontrolled pitch up, which in a high speed turn can rip yer wings off.

I'd consider going to a canard format if you want to squeeze every ounce of positive lift from every square inch of lifting surface.