You can find demos of the 3700 here:
http://www.casio-europe.com/euro/emi/highperformance/wk3700/sound/

The style demos are decent, but I hate the "voice" demos on this site because these are excellent examples of "lazy" or "half-assed" demos. I say that because the voice were "all" recorded at the "same" velocity level. They show absolutely "no" expression at all.

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.