That's a really good question. I noticed on the PSR's they list what..? 480 or so XG voices...?, but if you look at the QY sequencers they use XG voices but the voice set consist of 547 voices with 22 drum kits. So I guess the quality and quantity is different.

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.