We need to remember that everyone has a different idea of what "use" is. The two stroke guys like relativly smooth terrain where they can open it up. My group is a boondock crew of ripping up the skid plate over rock ledge and knocking down trees. Some ranchers and farmers mount a fifth wheel in their Avenger for their trailers. Whipper has evolved mind boggling comfortable long distance desert runners.
As for speed, when we get on a main trail, everyone seems to run wide open without a problem if they want to.
To Invent, you need a good imagination and a pile of junk. (Thomas Edison)