You know NS is as personal at a trigger for us Pisoleros.
I think HK themselves approve and use Meprolight (HK45CT).
Folks like Heinie and Trijicon too.
Depends on the kind of shooting as well.
Target, competition, Close Quarters Combat?
Personally I'm a CQC guy.
And have XS 24/7 Express Big Dots on all five of my Heckler and Koch pistols.
One of them being a P30 40 V1 Light LEM.