These tires have been great on all gravel, from crushed limestone to big chunky stuff. I haven't had issues on any surfaces except on the slip and side stuff: hard packed wet mud, low wet grass, and sand. I made it through those surfaces but I had to take it real slow. All tires will be a compromise somewhere but these do a great job of being good for a lot of conditions. I don't see myself trying a different tire. I don't want more or less tread. I'm also really liking the added control and stability of the 650's. Of course the added tire clearance is what most attracted me. My mtb is 650b too. Once problem though, my bike is in the shop getting the rear hub replaced. I did a very wet and muddy race and afterwards the rear hub starting seizing up. Yes I went through loads of deep standing water but this shouldn't happen on a new bike. Felt and my LBS are taking care of it (as they should). Aside from this hitch I'm loving the bike. This ride has a pic of it in the wild.
https://www.strava.com/activities/2060998530