Another fun tidbit from the configurator: Carbon ceramic brakes are NOT covered by Ultimate Service. And they note "Replacement of these rotors is more expensive than replacement costs of conventional steel/aluminum brake rotors". If Porsche parts costs are anything to go by (and it seems they are considering the option pricing is similar), try ~$4K per rotor compared to ~$400 for steel -- yeah, I'd definitely call that more expensive!
Nice understatement, BMW.
Add to that the caveat that "M Carbon Ceramic Brakes are vulnerable to damage from stones and other debris, and must be replaced if damaged or dropped", so if you kick up rocks on an off-track excursion or even nick the rotor while removing or remounting a wheel, you need to replace that rotor and maybe the one on the opposite side of the axle to maintain balance. Pretty pricey proposition, both upfront and over time.
I'd be worried that if I got them, I'd want to keep the car a bit longer than when they wore out, but not so much longer that I'd be able to stomach paying the huge replacement cost since I'd only use a fraction of the new set -- I could also see these actually hurting resale from prospective second owners not wanting to worry about that massive impending replacement cost. But a few reviews here have mentioned very early brake fade even on the street with the steel brakes, which suggests they wouldn't stand up well at all to track duty. Hopefully those reports are overblown or the issues can be fixed with better pads on the steel brakes like the M3.