I have strong reservations about the integrity of both types. I have two leaks after 8 years of service with the stainless steel clamps. My colleague at work has had three leaks in as many months, one causing extensive damage and mold abatement for which the insurance folks are required to make you leave and stay in a hotel room (with 4 boys). Both homes are relatively new 6-8 years service and in the same water system.
I found out that the tools are supposed to be calibrated every 30 connectors but usually are not.
My clamps seem to lose compression over time and I have one slow leak and one leak around the circumferential space between fitting and tubing. My colleague had complete parting of the band so that the leak was open ended flow after the PEX slipped off the fitting.
Mine seem to be under clamped as a result of tool wear. My friend's may have been over tightened by a tool adjusted too tightly.
Three engineers on my floor at work are seriously considering what it would take to replace their entire house full of these clamps. You have about two minutes from leak initiation to serious damage. I am totally thankful we were home, but have little confidence in this product.