Diki, I disagree with your assessment of triggering dynamics. The voice/instrument dynamics in the vast majority of arranger keyboards is strictly controlled by velocity - not pressure. Therefore, the weighting of the keys, if anything, would hamper dynamics - not enhance them.
Franz, Having played the S-950, only for a short time, they keyfeel is different from all previous PSR models. It more resembles the Tyros 2 and some of the older Rolands I played.
Key feel, at least for me, would have little or no bearing on whether or not I would purchase a particular arranger keyboard. It's what that keyboard sounds like that it most important. Whether it's made of cast-iron, stainless-steel, boron, carbon fiber or acrylic plastic is, however, a factor. I want something lightweight that facilitates easier transport and setup.
Speaking of carbon fiber (hijack), I got to play a couple carbon fiber guitars while in the keys - the sound was amazing, the fret fingering was very uniform, they never need neck adjustments, and they tolerate the harsh marine environment.
I sincerely hope the new BK9 works out for all of those that are currently anticipating the purchase of this keyboard.
Gary