I have held Wagos in my hand.
I've disassembled Wagos on my desk.
I've unhappily connected wires to them on DIN rail terminal strips in machinery.
I've been informed on this Forum that the clamp is not stainless steel, as I thought, but "spring copper" (my magnet picks them up).
They may spread stranded conductors evenly throughout the clamping zone, but that zone is less than 1/16", as shown in andy's picture.
I find it hard to believe that this puny, sharp edge would not eventually cut into the conductor if it was vibrated or rotated.
A wire nut provides conductor to conductor contact for virtually the entire stripped lengths. See how many hands it takes to just pull one apart. I've done demo, and seen that sometimes when ripping wire out, I can just about hang my 200 pounds from a conductor that's spliced in a box down the line without the wire nut coming apart.
What's next, sheet metal split bolts?? [Linked Image]...S