BK-9's action is basically pretty much the same as T4, PA3X, minus the aftertouch. Weight feels about the same, nice and crisp...

I think that's the word that best describes what the PSR's are missing - they really aren't hardly any lighter than T4, PA3 etc., simply more spongy, less 'crisp', if you will.

And, in fairness, the G70's action isn't very much heavier at all. My K2500's action is FAR heavier than the G70's. What made the G70's so good was, once again, how precise and 'crisp' it felt, but even more so, its shape... darn near full sized piano length, but without the piano's fake ivory overhang, black notes almost identical to a piano's, but just SLIGHTLY more rounded, and a very slight convex curve to the surface of the whites, with the corners slightly rounded off and the ends missing that overhang completely.

The end result of all this is something that, if you are used to playing a piano, didn't throw you any curves getting used to something significantly shorter in length for both black and whites, but had none of the piano's tendency to 'grab' your hand when you did palm smears and other organ techniques, which were developed on waterfall keys that have no edges to bite you.

Some day, maybe we need to do something a bit precise in the way of testing what force is needed to play all of these different actions. I imagine a weight placed on top of a long rod, dropped from a specific height a specific distance, and measure how much weight is needed to generate a full 127 velocity message would give us good data.

Were this to be done, I think there would be quite some considerable surprise at how close most of them are. I still believe the springing and overall construction is more of what contributes to the 'feel' of an action (along with its shape) than the actual force required to achieve a 127 velocity message...