HKs are one of those things where the more you shoot it, the more you like it. I certainly didn't much care for it at the time when I bought it. I only bought it because I wanted a .45. The HK45 seemed like the logical choice for me. It was either, get a lower end 1911, a CZ 97, or a top of the line polymer (subjective of course). So I went with the HK45. If you noticed the other choices I listed are all full steel framed handguns. I actually prefer steel framed handguns. In fact, the HK45 is my first and will be the only polymer framed gun I have. I love it, yes, no doubt about that whatsoever. And, I would never sell it. But, I'm just not a polymer kinda guy. For me though, that HK45 does what it needs to do, and does it extremely well. Now if HK comes out with a steel framed hand gun, I'm all ears. But for now, I am content with this one polymer HK45.
And the DA isn't terrible if you dry fire practice. If you just stick to the basics, you'll be fine. Buddy of mine challenged me to shoot his full size USP in double action at 7 yards. I had been shooting LEM exclusively for a long time when he challenged me for that. It was a one inch target at 7 yards. Hit it dead center the first time. It's bad, but it's not the worst, and if you have proper trigger control, you should be fine.
It's funny though. I practice the double action on my LEM now, not really for second strike capability, but more for finger pull strength. Hah.