I have owned both.
They are two different pistols, one being striker fired and the other hammer fired. One is also a safe-action type pistol and the other is DA/SA. You mentioned you own SIGs? Assuming you own the DA/SA variants you might be more comfortable action wise with the HK. Another option is to look at the Walther P99 which might be closer to what you're used to.
I'll make a last comment, and put on my flame suit as I do.
I have owned four Walthers, two PPQs and two P99s. 2/4 of those had some issues. Now I am a bad luck magnet, so in the interest of fairness I will say it might have been a fluke. But I have not had the same percentage of problems with HK. As always, YMMV.