That didn't last long.
Summary: Action is heavy and too different in feel compared to my N1X. Therefore, I returned the P515 for a refund.
Here is a more detailed analysis with some objective measurements of the P515 compared to my P125 and N1X.
I've wanted to try the P515 with the NWX action since I'll be playing the slab exclusively until we get settled in our new location (might be weeks, months, don't know) while my N1X is in storage. I never intended the P125 to be my primary. I'm more interested in the action (as a controller) and not the onboard sounds. No P515's available to try so I had to buy one from Guitar Center. I was a little concerned when I saw the damage to the box.
However, it was a false flag. No damage to unit. Good crumple zone in packaging.
Unboxed, plugged in...wow! Action feels a lot different/heavier than my N1X and P125. Keep playing, try different touch settings, wow! I don't think I like this. Comparing all three Pianos I begin to realize that the P125 action feels closer to the N1X than the P515 does. I still haven't taken any measurements yet, but my subjective feeling is that the gulf betwixt the P515 and N1X actions is too great compared to the P125 and N1X. Even the key surfaces (black and white) of the P125 and N1X feel the same while the P515 is much different.
Ok, it's time for some measurements. Is this all perception? I measured the weight to let-off (P125/515 just get the key moving), total weight to produce a sustained note, and upweight. I measured in three regions (just the white keys), low A, middle C, high C (and a few keys around them) Here are the results measured in grams.
|let-off Low A
|let-off middle C
|let-off high C
|sustain low A
|sustain middle C
|sustain high C
|up weight low A
|up weight middle C
|up weight high C
Those are the objective measurements and you can interpret that however you'd like. But for me it feels more natural to transition between the N1X and the P125.
I don't want this next statement to be lost so I'm going to highlight it.
If I didn't have an N1X and had to choose between the 125 and 515, I would choose the P515 because it's a great value.
It has good speakers, lots of features, and the action isn't uncomfortably heavy. However, given my circumstances, the P125 is a better option when I'm not playing my N1X. Hope this helps.