I've had my HK (in .40) for nearly 15 years. DA/SA with decocker. It now sits in a special place at home as a go-to home defense pistol for that part of the house.
I must disagree with it being the "pinnacle" of pistol quality. I became a little disillusioned with HK after dealing with this pistol. Factory trigger was NOT good. Surprised it left their QC as it was. Had to get a trigger job done on it to make it work correctly. By that I mean it was VERY rough and you couldn't double-action it on target. WAY too heavy of a slide, and the double-action springs require Bionic Man finger strength to pull. Teutonic over-engineering at its finest.
The only reason I got mine was, frankly, that was "the only" brand to get. It was one of the few with the external safety, which at that time I deemed important. The decocker is nice but not a must-have. The problem with the hammer is that it is a "half hammer" in that you can't manually cock it back without pressing the trigger to pull it back enough to gain purchase with your thumb. I understand why they made it the shape they did, but it needs refinement.
Trigger pull on mine is a bear - you can't make that first shot accurately due to the double-action spring. The single-action (aka fully cocked hammer) is crisp and clean. But that first round is going to go wide unless you have those aforementioned Bionic Fingers. My retired LE buddy and I discussed that one to death. We agree this double-action first shot is there to help LE in stressful situations to prevent accidental discharges. But for the non-LE person who isn't shooting it weekly, and for those without Bionic Fingers, you should store it with the hammer cocked and the safety on. Which leads to a plethora of 1911-style discussions about spring weakening, safety concerns, loaded rounds, etc. etc. ad nauseum... I store mine in the safe place with a full magazine and nothing in the chamber. I must slide the action to load a round.
The Euro-pattern safety on other pistols (aka the "backward" safety) just takes practice to get used to. My Walther's that way... not too hard, just takes some practice
Loaded round indicator is "iffy" at best. Simply isn't up to the same quick check-by-feel shape and operation of other brands' loaded round indicators. Requires removal of your trigger finger to check unless you break your grip, which is fine at the range but in a stress situation is not a good thing.
I agree with the magazine observations. They simply suck. They apparently make magazines to ATF specifications. Full-capacity mags for HK pistols are something of a fairy tale.
Prices for new magazines have kept me from replacing the crappy ones with increased capacity ones. There's lots of plastic in them that doesn't need to be there (to serve as shims to block full capacity?) Mine, now being nearly 15 years old, are starting to show weak magazine springs. I suppose they are taking a set, but one would think that HK, of all companies, would have springs with a duty cycle of more than 10 years. I have put perhaps 1000? 1500? round through it over the course of the last decade. Maybe more... haven't kept up with pistol shooting lately. So 10 years / 1500 rounds and she needs new mag springs. In my mind, that spells S-U-C-K. None of my other weapons, with older springs, have shown such low performance on the mag springs. Maybe mine were made on the Friday before Octoberfest? I have nothing to compare them to and I'm unsure for example how long 1911 springs will last. However compared to my Para 1911 I bought at roughly the same time, those Para mag springs are fine and I keep them loaded for the OTHER go-to in the house. Overall I suppose 10 years isn't too bad for a spring... or perhaps Canadian springs are better than German ones?
They aren't bad pistols, but you are paying for the BMW name brand with them, and personally with so many other GOOD competing brands out there on the landscape, you'll be hard pressed to justify owning that BMW when a Toyota or Chevy will get you there just as well. Unless like me at the time you simply had to have a BMW.