JB puts these cranks into engines that he builds for his customers and he doesn't want any come-backs, so he must trust them.
When you see JB fitting someone else's cranks into the engines he builds, then it is time to think again. The fact is, he started building his own cranks because he kept being let down by cranks manufactured by others (twisting, weights falling out etc etc).
The quality of the webs seems very high. They are full circle.