The YPG-635 has weighted 88 key Graded Hammer action according to: http://www.yamaha.com/yamahavgn/CDA/ContentDetail/ModelSeriesDetail.html?CNTID=5015193&CTID=205200

I really like the touch...it's the same as my P85, and with the upgraded pedals (LP-7) you can have half-pedaling.

I haven't played a Korg PA-588, but if it is the same action as their SP-250, which I have played, it is a very nice action...beautifully done.

Ian