I ride my CX bike with 35mm Gravelking SK (tubeless!) on a lot of singletrack. because it's a lot lighter than my mtb, it climbs like a rocket and FLIES when the trail is relatively straight and the dirt is hard-packed. I have to slow to a crawl to pick my way through anything twisty or rocky, so I am selective about that routes I pick when I am out on this bike. I know my local trails well enough to know what technical, chunky trails are only fun on the mountain bike, and I avoid those on the CX. if the trail gets chunky at all, I feel the need to stay in the hooks of the handlebar. that's fine for short sections, but it gets painful after a while, which is an indication that I need a higher handlebar for that sort of thing.
Here's from last night's ride: 38/16 gearing and I rode some long hills. my average speed would be a lot faster, but all the twisty singletrack I chose slows me down a lot.
I am working on replacing this bike with a something that has room for bigger tires because the "pizza cutter" wheels just don't cut it when the trail gets rocky at all. it kind of kills the fun. I am hoping for 42-45mm tires for more of a "monster cross" feel. I need a new frame for that.