Consider that all other Yamaha 88's come in at considerably MORE weight than the P85. I've noticed in the literature that Yamaha don't describe the P85's action as 'graded piano touch' like they do for others in the line. Ian, from playing the Yamaha line extensively, can you tell us what is different in 'touch' between it and all the others?
It seems that Yamaha have JUST as much problems as everyone else making a quality 88 at a weight under 40 lbs. or so, with this one exception. I smell something fishy...
BTW, you might consider that the P85 has no display, no full synth capability, no audio ins for mikes, very few buttons and controls (all of which add weight), and just expanding the case size (currently, it's basically just the keybed and very little else) to accommodate all the extra buttons and displays to the size, depth wise of an S900 would probably at LEAST double the weight.
Without paying through the nose for composite materials strong enough to not flex under the size increase of an 88 (it would probably take space age carbon graphite composites like they use in aircraft and hi-tech supercars), it is madness to expect an 88 arranger to come in anywhere NEAR the weight of a 61.
I played an NP-30, Yamaha's lightest 76. It was TERRIBLE
Not even remotely piano-like..! Not even remotely as good as a T3!
I think, from what I've read, that most of the 76 size arranger fans are realists, and understand that a quality 76 keybed ups the weight into the upper 30's, lower 40's. I think, in all fairness, what most of them want would be the MotifXS7's keybed. Big enough to play piano parts on, light enough to play organ on, strong enough to not feel like a toy...
You want to save weight? Drop the speakers. Everyone is using PA's anyway, and putting a quality arranger through those rinky-dink crap built-ins is an insult to the sound that it CAN make...