Agree with Alistair here,
As I understand from my P of F which was some 2 years ago now, I get it as the following.
The forward c of g limit is limited due to the stick forces required, although the stability will be better. Rear c of g is limited by stability, ie. too far back gives significantly reduced stability, but with the advantage of light stick forces.
If you imagine moving a 1 ton load from the rear hold to the front hold, then the all up weight of the aircraft remains the same, but common sense dictates it will take more force to raise the nose. That increase in the force required to rotate the aircraft, then means that a larger downwards force is needed by the tailplane.
This increased downwards force from the tailplane increases the aircraft's effective weight (ie. it's actual wieght plus the downwards force from the tailplane). Given the increase in effective weight, you therefore need more lift which means an increased takeoff speed.
If I recall correctly, that is,
regards,
Obs