To date, I have yet to hear of a single instance of a failure with the firing pin safety on VP9's. That said, I think it is useful for people to examine and theorize about the possibilities with things like this to continue expanding knowledge and potentially enhancing future designs.
As I see it, there are several factors at play. Historically, H&K seems to have always consistently or ruthlessly maintained parts quality. Unlike with some other manufacturers at various times (e.g. SIG US over the past decade and a half), the integrity of their individual parts has always been remarkably consistent. I mention this because, in designs that may be less desirable from a mechanical standpoint, to some degree you can make up a bit from those deficiencies by having excellent parts quality.
On the flip side, beyond parts quality, there is component design. Personally, I see the design of the VP9's fire control system as less desirable than Glock when it comes to pure safety. For one, the VP9 has a fully-tensioned striker. Most full tension striker guns are effectively like 1911's, just usually with some form of trigger safety.
Also, you have a firing pin safety positioned farther towards the rear, which means theoretically if a firing pin broke there is more mass forward of the FPS and unrestricted. That said, going back to the parts quality angle, I highly doubt we'll ever see an FPS that shatters and fully fails either, so maybe that less desirable (IMO) positioning isn't a big deal.
Additionally, the FPS and sear interact using one striker surface, so a single point of failure. Also, the sear movement is unrestricted, meaning inertia from a drop could
theoretically cause the sear to bounce and release the striker. This last point is purely my speculation based on what I see from the components and how they interact. To explain what I mean, take off your slide, press down on the sear, and watch it move. You can't do the same thing with say a Glock due to the drop safety shelf on the trigger housing. For reference, the unrestricted sear is also a theoretical issue in the P320 platform.
At the end of the day, the P320 has pushed the ragged edge of the striker-fired arena, and specifically the fully-tensioned striker realm. The wheels have certainly come off the rails with that platform. I think it's worthwhile to learn from the failings and potential dangers or deficiencies with that platform. If you want a fully-tensioned striker gun, the VP9 is probably the best you're going to get currently. If you want the safest, most durable, and most reliable striker-fired gun, it's probably going to be a 9mm Glock with an SCD backplate for safer reholstering.
Or, you could go USP or P series + LEM and bypass all of this.
Just ribbing people, all in good fun. At the end of the day, just avoid speed holstering, LOOK at your holster and be slow and deliberate about re-holstering, and you'll be just fine with a VP9.
