5'10. mine felt a little cramped at first. but with the longer swing arm and a arms it really makes the quad fit me better. i just ride on the back of the seat mostly.
adding the longer swinger let's you move to the back of the seat without standing it up every time you punch the throttle a little. makes the seat feel much longer when riding
I'm 6'2" and I fit just fine on my Blaster. I have handlebar risers to help bring the 'bars up to a more comfortable height. My Blaster has also been widened 4" total, and that helps it feel more stable.
I'm sure a longer swingarm would help me even more, but as of now I love my wheelies!