I'll kick in my 2c. I just traded one. I had put about 1500 rounds through it. I had it about 4 months, and it was my first non-inherited handgun. I loved it, but hated the trigger, so I put in the Apex, and that was a great trigger. Never had a single failure, and it shot great (although I didn't). Shortly thereafter I bought a gen to Glock 17. I like the trigger on the Glock a bit better then the Apex, because the Apex is a bit floppy with longer uptake, but in actual shooting (not dry firing), I did not notice much difference. I shot a bit better with the Glock, but I don't know why, because the perceived recoil on the SD9VE was noticeable less. In fact, imo, (which is worth nothing), I thought the Smith was a better gun then the Glock - nicer shooting, lighter, better ergos (much better).
So after getting a bit comfortable on these two (neither are carry guns for me, too big), I traded/sold both to try a H&K VP9. I was looking for the P30, but none were available (from an immediate gratification perspective) and I came across the VP9, which I was not familiar with. What I liked about it is that it is basically the Glock manual of arms, with different (better for me) ergos - more like the SD - and I wanted to try and HK anyway, to see what all the hoopla is about.
I love it, and think I am going to stick with the H&K for this form-factor/caliber (I am not a huge collecter, or I would have kept all three, as they are all really excellent guns - in my noob opinion - and all really fun to shoot). This is also my home defense option (the Glock was a gen 2, so no rail, and I like the option of a light for HD).
However, although there are differences, and the HK has some additional features, and a great fit and finish, and is perceived, therefore, as a "better" gun to some, in my experience, there is no significant difference in quality or shoot-ability. The HK has tritium metal sights, interchangeable back, front AND side grips (which I don't need, as stock config is perfect for me), and some other features, as I mentioned, but otherwise, I kinda wish I had just kept the SD and saved the $$ -- but not really, LOL - as there is some intangible quality to the H&K that I really dig the most, out of the three. Also, the ergos/feel are unique compared to these and other full-size guns I have experienced, and preferable for me. But if I were going to get a HD 9mm and was not worried about irrelevant "coolness" factors or fit and finish or ergo subtleties, I would just get the SD9VE, throw the Apex kit in it, and be very happy.
There is a lot of competition in the full-sized, striker fired 9mm format (wish the Walther PPQ was mass compliant, btw) -there must be dozens of options. From my limited experience, the S&W SD9VE is as good as any (except the trigger) - and I realize that this is supposed to be a budget, bottom-of-the-line option. But in fairness, I have done a fair bit of shooting with a few other brand's version - Glock, H&K, Sig, the M&P (doesn't shoot any better, and the trigger is better, but still not great of the two I way prefer the SD).
