The problems with your ladders had more to do with the fact that the Missions have single component ratchets which are just metal. Metal on that kind of plastic ladder will start to strip. Your cartels have dual component ratchets, which has plastic touch the ladder, so there will be no stripping.
The main issue was not caused by metal on plastic. because of the reduced contact area, from the angled ratchet, and the fact that the whole ratchet can be moved away from the ladder, when I got my bindings really tight the ratchet would slip. each slip taking away a little bit of plastic. sure that's where the metal was doing more damage than plastic might but the root cause was mechanical. there was always proof that only about 1/4" was engaging because that was the only part that would be stripped on the ladder. again, i believe this is caused by the crooked ratchet. plus, if the both materials were plastic then they would both be slowly worn down by this slipping to where I would need a new ratchet and ladders.
I actually had a burton rep try to tell me the same thing you just did. but he had nothing to say after I explained what I saw happening.