I read it at Eileen's Yamaha Keyboard Players website. In fact, she confirmed what someone else said.
Has Yamaha confirmed this about the keybed in its SPECS I would assume if it was improved they would state it as a upgrade in their feature list on the S970? or is it that people just feel something different because of its "newness" vs a used keybed?......I would have to personally play one to be sure but I highly doubt it....
I'm sorry I don't know for sure. It's just something I read from a couple of people. Guitpic1 seems to confirm this, though (see his comment above). On Motifator, I also read that if you change the velocity sensitivity, the keybed will seem to be different. Maybe, it's just the better sound affecting how we think it feels. Or perhaps, the keys are made with more plastic.