Yep, I'd rather know someone's biosecurity practices than see a piece of paper that says NPIP. Rather see both. But always a chance something could happen.
I do think NPIP is a good thing.
But it only gives a snapshot of the tested flock on the day the sample was tested. NPIP only tests 1-2 times a year I believe.
So really only as good as the biosecurity they keep. Nothing is 100%.