i'm betting she would be fine on the 08' sportsman 400 HO as it steers alot easier then the 500's do and she can drive that until adulthood. i bought one for my wife becuase the sp 450(same engine,455cc as the new 400 HO) felt to big and hard to steer for her and the 400 was the perfect size. just a thought.

 

you might be better off buying something used ,that way when they do grow out of it you may be able to sell or trade without losing as much. don't forget the body armor, even the green trails have that dropoff

 

HEy use good sense on kids quads.My son has grown up racing and trail riding.At 10 he was on a 125 Yamaha Breeze and it fit him great and was a capable machine.Graduatd him at 12 to a 2001 highly modded 250 Trailblazer and he handled it good.Then went to a 350 Warrior now he is on a 2001 400 Sportsman.Just because they have experiance and CAN ride a big machine doesnt mean they NEED to.
I would put you 10 yr old on a 250 Recon for a yr or a 300 Hawkeye if 4x4 is needed.Then when she is older step her up to a full size 4x4.

 

Just like to add a comment on the Hawkeye. I have one and it has been great for my kids - girls 14 and 10; son 12. It is the smaller frame and is much easier to handle and steering in a breeze. Maybe a slightly used one would do the trick. Just a thought.