I find the Kodiak 450 to be to small, I'm 6'2" so I like the larger Kodiak 700. It's a better fit for a taller or heavier individual. The 450's suspension I think is too soft, gets mushy on downhill turns and can be dangerous if going too fast. I really like the feel of the suspension on the new Kodiak 700. I find it quite a bit stiffer. I bought a Kodiak SE so the suspension is adjustable. I'm 225lbs and left the suspension on the setting that came out of the factory and find it to work great. Quad has lots of power to accelerate even up steep slopes. I don't need anything more than what it produces. The 450 works great too but obviously it won't have the jam of a 700.
My previous ride was a 2009 Grizzly 700 SE, I like the kodiak a lot better. Lower center of gravity (fuel tank moved), I love the new large storage where the tank use to sit. Better turning radius, stiffer suspension. Feels less tippy. Twice the fuel economy. Nice large racks (that's my weakness!) I just wish the SE model came with LED lights. I have only driven the 700 for three trips but my first impressions are very favorable. My wife likes her 450 too, however she got on my quad and turned it around the off load point and liked it. Don't let your wife ride your quad (could cost ya more money!)