Hi Chuck, those are both very innovative and functional designs. Me likey! How about you call it the Chuck Lock? I'm not sure which one I like better.
The second one seems simpler and looks less bulky, so I definitely like that. The first one (with the metal) looks, in my opinion, like it would wear better though. Seems like pulling on the tab to release the knife thousands of times would wear less on the body of the sheath, and could be maybe more easily replaced. Maybe if you used a little piece of kydex there instead of the metal so there's no danger of metal on metal contact between the metal tab and the blade.
No matter what, I like seeing new designs and that's a new one to me! :thumbup: