FWIW, I have two HKs, an HK45 and a P2000SK in 9mm. At least for these two, I don't think they're ridiculously huge for what they are. I can definitely see that criticism for the USPs though. My thoughts on them are:
negatives:
- The HK45 is pretty flippy and it took a bit to get used to it.
- The DA trigger in particular does suck. I don't get why SIG and CZ can figure out DA/SA triggers that feel so much better but HK can't.
- The HK45 mag prices are ridiculous though the P2000SK magazines aren't anymore expensive than SIG mags.
- On the HK45, popping the slide release out to field strip is a PITA because it's recessed on the other side. The P2000SK isn't like that.
- stupid "night" sights on the HK45. I replaced them with Trijicons.
positives:
- Neither has ever malfunction, period. I've had Glocks, SIGs, an M&P, 1911s, etc and all had malfunctions of one form or another. Neither HK has ever failed to feed, fire or do anything but what they're supposed to. The HK45 has had everything from Wolf to UMC to Ranger +P through it.
- If I had to go swimming in the ocean with a gun, I'd pick an HK.
- I actually think the docker on the P2000SK is a good idea. It's ambi, more or less and doesn't add any width to the gun.
- I like the mag release.