I own both. German is stock V1 and my US made has GGI work done on it but there is absolutely no difference in reliability between the two. Granted I didn't do a Todd G. test but I haven't seem one hiccup in either of them. The only difference I noticed is the "HK45C" that is engraved on the slide is engraved deeper on my German slide than my American slide... My American made one seems a littler lighter too but I think that's due to the LEM and the GGI work more than actual mechinical differences.
If you need a push to get it consider this... Todd G used a American HK45.
I have a German 45c and have shot a friends American 45c several times. This was not a thorough comparison by any means but I didn't notice any difference in performance or reliability either (similar experience to DareBear). I'm no Todd G but for what it's worth I have been shooting HK's for many many years and definitely wouldn't hesitate to get an American 45 or 45c.
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