Nord uses only M or H versions. I don't think they've ever used an L (which Kurzweil uses, and happens to be my favorite of the bunch).There are 3 other incarnations of the TP40, the TP40H (Hard Touch Feeling), the TP40M (Medium Touch Feeling) and the TP40L (Light Touch Feeling). As the action of the Piano 5 is not graded, it must be one of these three.
But Nord do their own implementation of it, I assume, like they have done with Kawai's RHIII (RH-N is what Nord calls it, I believe).
Yes, I've seen things about Nord tweaking the action for their needs... and I've seen that mentioned in regards to Dexibell as well. The exact nature of these tweaks is never described. (It's also unclear as to whether this is something that Nord/Dexibell physically do themselves, or if they have Fatar alter something for them in production, but that's academic, really.)
As for how Nord likewise offers an altered RHIII, again, it is unclear. It could be simply that it is an ungraded version of an action that would otherwise be graded, or there could be other modifications as well.
There's always subjectivity to this, of course, but I wonder if he'd ever played a Nord Grand, which Nord themselves would tell you should feel even better to play than the Piano 4. I'd also be curious about what else was in the shop at the time, i.e. whether he'd (yet) had the opportunity to play, for example, the Yamaha CP88 or Dexibell Pro 7 we've been talking about here. Still, obviously, each of us could conceivably play the same three boards and come up with a different answer to the question as to which plays the best!The guy in the A&C Hamilton video I posted was actually already playing a Piano 4 on one occasion that I went into the store, he was playing it for his own enjoyment and it sounded amazing, no other person was on the sales floor at the time. He was in 7th heaven and even said it was the best DP in the shop and the best he had played.