My 6.5-06 burns 49grains of powder to propel a 140gr. Berger to 2950fps and my 270 burns 61gr. powder to propel a 130gr Ballistic tip to 3100fps.
As Bob says, to practical hunting distance there is very little difference in performance.
One thing that is noticeable is the 6.5 is more pleasant to shoot, less muzzle blast, recoil etc...
I believe the 6.5-06 advantage shows in long range target shooting.
Hunting, flip a coin.
