That day, we climbed almost 5000ft with two steep descents (46mph on my computer). Both clinchers were squeely and noisy on applying full brakes. But, we all made it back to the parking lot safe.
It's not the amount of climbing or the speed on the descent, it's the amount of braking. I've done a 2 day race with 29,035 feet of climbing and many 50+ mph descents that is totally safe on any carbon clincher- the descents don't require much braking. OTOH I had a tire blow off an older Reynolds carbon clincher while doing a short ride near my house. That road is steep and has a lot of tight corners. Even knowing it well there's a lot of braking involved.
When I get my basalt brake tracked clinchers built I will try them on some easier roads before I do that descent near my house.