...what does this this do that the 270 does not?
Not much, actually. But the 6.5, being a target caliber, has more bullets to choose from. I really like my 6.5-284, which is pretty close to the 6.5-06, probably a notch behind the improved version. I shoot 140 SST's at 2,950 fps.
From my observations, the .270 is a great hunters round, the 6.5 clones, more gun nut stuff. My 6.5-284 is more accurate than my buddy's .270, but out shooting game at long range, no real difference.
DF