I'm fortunate to have LOTS of gravel around the area that I live, so ride quite often. As others have mentioned, it certainly depnds on the consistency of the gravel/dirt. Generally I ride a mtn bike as well, and often not have Kenda Small Block 8's on both front and rear. Most of our roads are remote, but often used with people driving them, four wheelers and snowmobiles in that time of the season. It's too bad that you didn't live closer,the shop is hosting its annual Turkey Tro ride next weekend and the majority of it is on gravel. However, the last ten miles are on pavement, but the fun part is that it is all downhill

Whatever you decide to Catrin, have fun relax and take in everything around you... it's certainly a different experience. And "yes" some people do ride 'fatbikes' in some of the gravel races.