WieWaldi So my final question is: how about the differences concerning the playability, control and repetition speed?
For some reason, discussions on the digital side of things always seem to veer into a spec comparison, but discussions on the acoustic side only very rarely sway this way (except perhaps from former digital converts). I'm generalizing, but based on my years on the forums, this seems to hold true.
What I hear on the acoustic side tends to be a very different thing — it's all about the sound and musicality of what you are producing. Often, a high quality upright piano might be recommended over a smaller grand regardless of the action.
To bring this into focus, I have a Kawai Novus NV10 with a Japanese-made Millennium III grand action. It is easily one of the greatest actions that can be had in a digital piano. I also have a Chinese-made upright piano, a Ritmüller UH121R by Pearl River. The upright piano is also cheaper than the NV10.
The upright piano is easily the one that we would pick day over day to play. The music it makes almost never stops (literally, the strings are always vibrating) and the specs of the action matter less. What matters is the sound that's produced and what we're hearing while playing but the action is almost never the limiting factor here.
Admittedly, specs may matter at higher echelons of piano playing, but I don't have much experience with that.
If one has the luxury of choosing between an upright piano and a high-end digital, I personally would sway strongly towards an upright piano. In retrospect, I wish I had.
