I am a kydex guy. I have been a kydex guy since the early 90's when shooting buddies brought me back "Mad Dog" kydex. I have been a kydex guy since Blade tech had the ixthus (fish) stamped on everything he sold.
I am wearing a kydex holster right now ( legacy graith/mastermind tactics).
Kydex is great right up until it cracks.
The magic of RCS is that they came to understand that and went all in on the injection molded stuff such that cracking and thereby coming out of service at the worst possible time is all but eliminated.
Please post up when you get these mag carriers in hand and have wrung them out a bit.