Welcome to this forum. We don't see "1" posting very often.
From a rough riding / jumping / bumpy ride perspective, the Pred-50 won't handle it. I've read many posts from Pred-50 folks stating their A-Arms bend, tie rod bends, etc. etc. If your "young rider" needs more fast speed for smooth riding surfaces, then you may want to perform a few performance mods to it. Little things like CDI, Air Filter, Pipe upgrade (if they make one for it) will give it more top end speed. Possibly to satisfy his needs for the next 2 years. If your "young rider" does rough bumps, jumps, corners, etc, then you may want to consider getting him a 90cc unit in the future. The Pred-90s (and other 90s) are made for rougher riding conditions and can be modified for unique riding conditions with less hassle and cost.
Hope this helps...