Did you see his video showing the design flaw in the action? The flaw is more of an issue if you play classical music. I think he found there was an issue with the weight of the black keys. It was an interesting video.

Sqk
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GEAR: Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller). SOFTWARE: Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.