Yamaha DX-7 30 lb
Korg Triton 30 lb.
Fantom G6 32 lb.
Don't think 5-6 lbs. makes that much of difference? Put a 5 lb. bag of flour on your keyboard while you play!
Unfortunately, Ian, if it were as easy as turning up the volume and velocity sensitivity to get the same dynamics and attack as a hard hitting rock or funk player (most of the greats grew up without great amplification in loud bands - it's part of the 'style'), there wouldn't be an 88 wooden MIDI keyboard on the planet!
I'm sorry, but off the top of my head, I don't think I can think of ONE great star keyboard player that plays a PSR type action (other than the great players we have here
Heck, even Liszt use to have a spare PIANO on stage for the numerous times he broke piano strings playing his music. I suppose he should have just played lighter, too?