The PSR-9000 would most likely have the same size keys as the PSR-740, and the 2000. The 9000 Pro has actual full size keys. The Pros keybed was taken from the Yamaha EX-5. It has great synth action and true key size..

Squeak
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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.