In the WEC bmw rides in E2 and E3, (was last year also Erik anderson had the 480).
But i dont think ik will be out for public, but if it was , then look at speedbrain.de they have most of the factory things.
Only thing it would make sence for me is that the rpm is lower, so for long distance rally things etc. For enduro etc, dont know, a 250cc would make sence for me.
But i road a 440cc drz for 2700km throught easterm europe (rally) and that was ok, more power then i can handle.