Kick bikes/kick scooters and IT band syndrome

A bit of background: Both knees are pretty well shot. It's IT band syndrome, which means anything requiring more then about 45 degrees flex at the knees will cause pain.

Because of this, riding bicycles is out of the question, but I've been hearing promising things about adult kick bikes and kick scooter. By adult kick bikes and kick scooter, I mean the Xootr Street, Kickbike Cruise Max 20, and similar vehicles. For those of you who have ridden them, how hard is it on the knees? I don't want to spend $$$ on a hard to resell item only to find out it's one more thing that aggravates my knees.