Specs:
http://www.korg.co.uk/products/professional_arranger/pa588/pa_pa588_specification.asp

51 lbs is quite heavy. That's almost double the weight of the PSR-S910.

I think all of these arranger companies should learn from Casio. The lowest end Privia has 88 keys and weighs just over 20 lbs. and has weighted keys. I doubt that it's the best hammer action out there, but it's portable and has speakers, albeit pretty crappy ones. Be careful though, the very lowest model doesn't even have a midi output.

I myself, love the weighted keys for piano, but not for anything else. I especially prefer the light keys for organ.

Beakybird