There is no such thing as a bad H&K. You will not have any problems, seriously, I have never heard of any H&K owner utter a single complaint and I know about a dozen.
The Sigma on the other hand, well !!!, as someone who shoots polymer frames extensively, it aint no Glock ,nor is it a Springfield XD, not even close, but thats just my opinion.
I wish you much success with your H&K, be it a compact, USP, or whatever, like I said, the name says it all.