From my experience, almost ANY key-bed is far superior to the entire PSR lineup. The only one I hate more is the Casio WK series.
It's not a question of light vs heavy - it's the spongy, feel and the short throw that bugs me. It's the only think that's kept me from owning a PSR in many, many years. If they put a better action on the PSR lineup - I'd be back in a flash.