I played the Canadian version(DGX-620) a few months ago in Halifax, N.S....actually it was a prototype...and came away with similar impressions as you did.
The action was, by far, its best feature...followed closely by the terrific piano sound.
I also thought it was very well made and of high quality construction...especially considering it was a prototype.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.