stick with known brands or companies with a reputation for standing behind their products if you're worried. A lot of manufacturers have a crash insurance you can purchase as well. Carbon is not indestructible, but its pretty tough. There are lots of people who have been riding carbon bikes for many, many thousands of miles without failures in all kinds of abuse. This is not new unproven technology. On the other hand, I wouldn't completely rule out AL and lightweight steel until you've tried them all and compared how they feel to you.