APC and M/A props toss a blade easily when encountering an obstruction. Not so with carbon fiber. Before they let go they transfer A LOT of energy to a firewall.

The larger APC props act much the same as the C/F props but not quite as bad. Ralph, even APC recommends against multi bolt drilling their larger props. I have hundreds of APC props around here and all of them drilled, but it's not recommended.