I have two Langdon Berettas with np3 (elite LTT and a Px4CC) on the internals and mags, with one more LTT on order. I’m a fan. Comparing my Px4CCs with np3 and without reveals, as others have said, more an increased smoothness than anything, though I haven’t scientifically measured the pull of the two. For me, the np3 is about protection and durability.
Based on how the np3 mags feel and how I manipulate the slides on these weapons, I don’t feel like I’d hesitate all that much to np3 a slide, other than for cost reasons when cerakote is less expensive and also seems durable. But if I ever try it I’ll do it on my nightstand 92 first, rather than one that gets fired in rainy matches.