The one she rides now doesn't have a hand brake, so I think it would be a little too sketchy for my liking - though I have no doubt she would love the speed :D
Check out Silkeborg Bikepark when the brake is fitted. With the towing strap it's really fun for the small ones to have a go again and again. We live next door to the park.
We did it on the running bike as well :)