I bought a Kawai ES8, and while the sound was great, the action was unable to manage the Bach Prelude & Fugue #2 in C minor:

https://www.youtube.com/watch?v=vcC4Thug-h8

Whenever your hand goes "in", there isn't enough leverage to play the black keys, leading to complete misses. On a few grand pianos, no problem.

I ended up returning the ES8 for that reason.