I hit some nasty worn away/rocky/rutted fire roads, sections of dry riverbed and some flowing singletrack this weekend on the cross bike.
2-3" sand was my only nemesis on 700x30 Bontrager Jones tires. No big knobs on the tires and too narrow. My skills are poor so the sand did me in. I was fine on the flowing fun singletrack but a "no brainer" trail on a FS bike turns into a real concentration camp on a cross bike. In some ways more mentally stimulating. I didn't blast down anything so the climbing was the fun part.
Def did fine. I want to get some knobbies the fattest I can fit (38, 40) on my Redline now for total offroad days. I'm not as interested in bombing downhill anyhow so flowing XC is my goal.
Cross bike, see some nature, get a workout in, and just have fun. I seriously think my MTB is in danger.
Go for it.