I have an off brand cf shaft I bought from someone on the forum, apparently he bought a batch from some Chinese source. The level of deflection is off the charts, so much so that if it wasn't 12.5 I'd be trying it as a jump shaft. (I really have to try jumping with it before it goes in the trash.)
I think everything a company does to get lower LD raises the chances the shaft will fail so hopefully the company answers the phone when you call with a cracked shaft.
I suspect it would take a hammer to crack my off brand shaft, it will outlast dirt.