With the heavy bolt in the Scorpion I notice the inertia as it cycle. Not significant yet clearly more gun movement then the MPX. Neither of my MPXs has had any issues with Gen 1 or Gen 2 mags. I had an occasional failure to eject on the Scorpion using Magpul mags - apparently they can drag the bolt and there is an easy fix. That said, I like the ergonomics once you swap the safeties. CZ also beats MPX on mag prices and availability.

On the Copperhead - I tried the side folding pistol brace and liked it better than the telescoping. More comfortable and makes the gun a little shorter when folded.