On the 450 you would most likely need to raise the bars up to make them comfortable.
the 450 is lighter, and the 450r would come with wider a-Arms already saving some money and making the bike handle better then a normal 450 or a 700.
I like the 700 I have for sure. I love the torque, and you can get more power out of the 700 easier. The 700 tends to be top heavy and tippy in the corners, so it requires some skill to lean, and kick the bike around.
One of the questions would be is your/their style of riding faster, more carving the dunes, or more cruising. The 450 is going to shine a little more in whoops, and at speed (It's a race bike after all) and the 700 (stock) is more of a cruiser, but has the power and speed to keep up. You just have to pay good attention to keep the 700 from tipping over in the turns at speed.
I have quite a bit of money into my bike, with axle, A-Arms, Shocks, Exhaust, Tuner, Intake, Piston, and cam. but I LOVE this bike. This is my first true duner bike, and I pretty much learned how to ride Dumont on it. I prefer the Raptor for the torque, and potential of the bike.