Not really as bold as you might imagine.
CF wheels are banned by every racing organization you can think of. F1, MotoGP, the pinnacle of their respective sports, have outlawed them.
Both of these sports used forged magnesium, which outside of possibly beryllium of which the dust is deadly to humans and the material immensely costly, is the best material for a racing wheel.
CF when developing stress cracks are practically undetectable. There is no means of non-destructively testing a CF component. (This is why only MotoGP, where the teams all have big bucks and will scrupulously throw away rotors at their recommended service interval, or after a crash despite no signs of damage), allows carbon rotors. Magnesium/aluminum can be x-rayed, and especially in the case of alumiunum, have significantly more ductility in the material, meaning you have more time to catch cracks.
CF also has to be very well designed to be strong on all load axis. The BST wheel, which I've gone over in detail, has a serious design flaw in how they connect the inner rim spokes to the rim outer. Basically, in their design, all load that is being transferred between the inner and outer goes through resin only where the two are bonded.
If you surf the internet boards, there are several instances of catastrophic failure of these wheels.
Last week, a member of another board I frequent, fireblades.org, had a CF clip on fail catastrophically on the race track. This is not to say metals don't fail, but they're typically a much more forgiving material.