I agree... think how many people buy the comfortsport just because they had a graco infant seat, loved it, and figure that they can just buy any graco seat and it will be great?
It's not a lot more than the comfortsport, so I could see a lot of people seeing why not go ahead and buy this one instead... even without the taller shell, better cupholders (though that will help pursuade the ones who think the comfortsport will last long enough), and higher weight limit.
And as long as that seating area is indeed comparable to the Marathon, we'll be able to recommend something besides the Evenflo Triumph, the Radian, and the Truefit, all that have quirks (knobs, sometimes hard to install, hard to access harness adjuster) that people can choose from.
Of course, then I just also keep thinking that the more submersed the market becomes in seats that hold kids in harnessed longer, the more people will stop and think before rushing to booster at 4 and 40 or (MUCH worse) 3 and 30lbs.