Yes! First, if you haven't spent much time on gravel, you will be more confident and sure-footed on the MTB. Second, you will have a much more comfortable ride

Yes! First, if you haven't spent much time on gravel, you will be more confident and sure-footed on the MTB. Second, you will have a much more comfortable ride. As others have said, it will be a bit more effort, but the improved confidence will probably do more for your overall speed than a skinny tire. I would however lock out the rear suspension, and probably the front too. The high volume tires at the right pressure will likely provide all the suspension you need for gravel and your pedaling will be more efficient. As far as being mercilessly mocked, that reminds me of an old adage. We spend our youth worrying about what other people think. In middle age we decide we don't care what other people think. As we get older, we finally realize no one was thinking about us.