Phenolic vs Steel caliper pistons

[koda2000]

I've only ever had one vehicle that had phenolic piston calipers. I guess the thought was that the phenolic material would not transfer heat to the caliper and brake fluid as much as a steel piston. That sounds like a good idea, but in practice the phenolic pistons seem to always crack and crumble. I replaced the calipers on that vehicle with w/steel piston calipers when I noticed pieces of the phenolic pistons had chipped off.