Check out the overall length of the Summit 850 165 (140") and the Summit 174 (140.9"). The extra track length doesn't change much in terms of it "sitting further back". I'd say it's a pretty fair comparison.
Edit:
I just checked the Polaris, it sits at 142" overall.
Overall. So ski tip to rear bumper? If that's the case that doesn't mean much. Some of these sleds have more tunnel and bumper length behind the track then the others