Piano sounds are a subjective and personal preference.
I played them both side by side through the same speaker system and I preferred the Tyros2 piano over the G70...it was more refined and cleaner sounding to me.
I also preferred the keyboard feel on the Tyros2.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.