First off, as Im sure he is aware, alot has changed in the last 16-17 years. For that matter, alot has changed in the last 8-9 years...which is the amount of time I was without a bike. You may have to explain how a four stroke is no longer for chugging around trails (with a few exceptions, ie XR). If he was going to ride only trails, I would suggest the XR400, but since he wants to do both, he may need to go with a CRF250 or similar. It depends on how good of a rider he is. If he still has skills, he may want a 450.