Well, I do certainly see the similar cut on the slide that you are talking about, but it seems a minor similarity to me considering the two guns operate totally differently. I would guess, that if Sig did in fact look at the cut on the slide of the PX4, that they probably evaluated what it was for. It's a way to shave off some metal where it may not be needed, and thereby save some money on materials. It also shaves some weight off of what is meant to be a carry or duty gun.
Well anyway, thanks for explaining what you meant.
Ladies, please simmer down. It's a Glock.
^^^^ Useless comment, and inflamatory for no reason........ To say it is a GLOCK, is like saying a Ruger GP100 is a S&W 686, so simmer down. To assume the same build quality will come from two different manufacturers is folly. I'm not saying one is better than another, just that you can't assume they will be the same, or even that minor design differences that you may not see in the picture may not make a difference in durability, reliablity, and shootability.
Also, the HK uses a paddle type mag release, which is highly useful for someone like me who has large hands, has issues with having two much finger on the trigger as a result, and also as a result has issues with the tip of their trigger finger getting beat up by a normal push button mag release when firing. I got rid of an FNP45 for just that reason and switched to an HK45, which solved the issue. In addition, the ergos of GLOCKS are what turns a lot of shooters off to the brand. The HK ergos are widely liked by many shooters, so while I'm not saying it is better than a GLOCK, it does offer a different option, and one that is more customizable.
So the bottom line sir, is that the VP9 is most certainly not a GLOCK. It certainly shares many design elements as a GLOCK, but it is not a GLOCK.