I have shot the basic Umarex non blowback one.
It's good and powerful.

I have the KWC model which is fine and blowback but less powerful.

I have the WW11 Umarex one which doesn't work very well although it seems to be a roughed up version of the KWC.
It struggles to blowback and you don't get many shots.
It was a bit better after I lubed the shuttle etc and it may wear in.

If there is another model I can't help.

I'm not a Luger fan and recall that TV show where a Luger fan and an ex US Marine using a 1911 did a trench warfare course competition.
The Luger was properly humiliated and the fan upset.