Nigel, I wouldn't be one bit surprised if those are the same keys from their current arranger line. These synths appear to share some hardware in other areas from their arrangers as well.
Nick over at Sonic-State flat out asked the rep if these new models are sharing Casio arranger technology and the rep confirmed it. To me that's a serious WIN WIN right there. That truly makes these new Casio's hybrids. They've merged a VA synth with a bread and butter performance synth, added a step sequencing groove box, AND are utilizing chord recognition from their arrangers. That's a lot of synth for only $499!
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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.