The 6 matches up very close with SVT... the extra 250 lbs cancels out the extra 20 HP and the 17"/thin sidewall tires help with sharp turn-in for the "perception" of equal to better handling. The lat gs and lane change speeds are slightly off SVT and I suspect push comes to shove, if you put the 17s on the SVT it will make more clear the benefits of shorter wheelbase and less weight. But "stock v stock" I agree it will come down to driver on EITHER the road course or drag strip. The 6 has a bigger back seat though. But, I like SVTs looks better...anyway, it would be a tough call...
And I also think I would prefer the 6 (or SVT!) to the altima or accord, despite the power deficit...superior all around package. The 6 in fact looks a bit like the new style Mondeo ST220...and its as close as we will see as a next generation CDW27.