Ellsworth

Overall I am still liking the Manker as a key-chain knife, but after some daily use here are the downsides.

Once the blade worked its way 1/16" out of the frame while in my pocket. I assume it was caused by a key pressing against it in the right spot and at the right time.

Twice I have reached into my pocket to grab my keys and when I grasped and pulled, I felt that a finger was touching the blade and causing it to slide.
I stopped my movement and re-positioned each time. I am unsure if the blade would have depressed off the rear retaining tabs and slide forward, if I had kept pulling on my key chain.

As a stand alone in the pocket, or in a pocket with something like a wallet and not a bunch of keys, the above should be non-issues.

I'm going to stick with key-chain carry, until it sticks me.

I did add a small amount of tape to the inside surface of the lever arm.
That has significantly increased functional tension, it now locks up more securely in both the deployed and secured position.
YMMV. There are knives of similar design out there. Some have a wider lever arm, which would increase friction. And their lever arms may or may not have more spring (apply more pressure against blade) than the Manker.

In the pictures you can see the other knifes I have daily carried. All are heavier, some are a bit smaller.