It takes big stones and no fear to ride moto, enuro or trials. Neither of which I have. I hurt myslef bad enough on my Suzuki 185 dirt burner just playin around, no way I coulda raced.
Back in the day I about bought a 250 trials bike, just because it was so cool not becasue I wanted to do trials ridding. I think trials is about the hardest there is. Up and over boulders that are bigger than you are, crossing streams on logs all while being judged on your style. Tough stuff.
Another motorcycle racing that has kinda caught my intrest is the
combination of moto and grand prix style. Part of the course is regular moto X and part of the course is a road race track. Talk about how to set up your bike, that would be tough.
Bonk what you are speaking of is called Supermoto. They run it in the off season of all other series, supercross, moto x, road racing, flat track, etc. If you ever catch one of these races it is usely fielded with some of the best riders from all of the mentioned circuits. Awesome to watch for sure. A local from Ottumwa by the name of Matt Burton travels west in the winter to run supermoto. And does well.