I have played the DGX-620(625 in the USA)...it is awesome.
The action is Graded Hammer...as good as it gets.
The piano sound is the Live Grand from the Tyros/3k.
The one I played(this past weekend) was a prototype but in essence a production model...it was the only one in Canada.
Very nice piece.It is not light,nor was it meant to be...it is a home piano,not a portable keyboard.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.