I think you need to be more specific. In general, PN is happier in cooler climates. Grapes from cooler climates typically have higher levels of acidity because heat accelerates the degradation of malic acid during the ripening process. In addition, partly due to dehydration, heat makes the sugar concentration go up. Malic acid is harsher than tartaric acid, which is the predominant acid in grapes, so with more malic the grape also tastes more acidic. So if you get a PN from a cool climate picked relatively early, you probably get more apparent acidity.
But all of that is general. You can grow PN in warmer areas or let it get riper than your neighbor and it just won't seem all that acidic. If it goes through 100% malolactic fermentation, it will seem softer. If it's fermented after being destemmed or whole cluster it's going to seem different. A cab from Bordeaux in say, 2004, is going to seem and will probably be, more acidic than a cab from Napa in 2004, especially if the latter was picked really ripe.
So if you're talking about PN and cab, you need to specify the region each came from - Napa/Sonoma PN vs cab from South Africa or Bordeaux is different than the reverse. And the winemaker probably has as much to do with it as the region. No idea which is best with acid reflux, since thankfully I don't have that problem.