Minor nit-pick but the horns on the 500s are K3Ls. PAR doesn't have any K3Hs. The L stands for low profile manifold. The K3H has an elevated manifold. They both play the same chord. (I know you already know that, Michael; I'm just stating it for the benefit of everyone else.)D'oh! I knew that. They are my next favourite after the K5L/K5H.
I've noticed that a lot of K5L/K5Hs have a slightly sharp #4 bell (before they erroneously started using a #4a bell, which is way flat) and the video was one of the few I'd found with a #4 bell playing the proper pitch.