what you say makes sense with the whole trails thing, but have you thought about the weight difference? bikers try to be as light as possible, but you with your moped and pack will probably weigh anywhere from 250 to 450 pounds depending on how big you are. that's in comparison to 150 to 250 pounds depending on the biker.
plus i doubt bikers are going down many trails at 30. have you gone through a parking lot full speed before? it seems like crazyness. multiply that by like 4 for the trees flying by your head.