Btcom, you said: "the S90ES is a synth it contains the best sounding Grand Piano sample of any Yamaha or Roland digital."
Well, this is where everyone's taste seems to be so different.
I am sorry to disagree %1000... concerning the S 90ES.
1) The "Natural Piano" sound of the S 90ES was my favorite...
2) the S 90ES grand piano sound is horrible in my [humble] opinion...
I wanted and was looking for the best Grand Piano digital sound. That is why when I went to buy my HP-207 (I knew NOTHING about Roland!!!) I did try some digital Kuwai... not bad at all... I tried the Yamaha Clavinova series... I didn't like the sound much and the keyboard is horrible...
...then I also tried some grand accoustic like Kawai, Yamaha and Steinway. Kawai grand accoustic were a disaster! Yamaha grand accoustic are great! Steinway was....ok (it was only a $60,000 one ?).
When I tried the Roland HP-207 I totally fell in love with both the sound and the keyboard action and feel.
Anyway, Btcomm, in order to go back to what you said, I am not really sure what the "wave room space" mean but I can assure you: the Grand Piano sound on the HP-207 is A-m-a-z-i-n-g ... it feels like a) I am playing a grand accoustic b) I am getting the sound of a grand accoustic.
I think Roland managed to do something that no one has managed to do: the sound sampling AND the keyboard action... they are in total osmosis. I wouldn't want to play on something else, only if it is a real grand accoustic
I'm used to playing songs on the S 90ES which sounded OK... now thru the HP-207 they are ALIVE... the piano solo for instance from Elton John "I need you to turn to"... that is a real test for a digital piano!
The S 90 ES is a great keyboard to start with but I only cared about the Grand Piano sound and the HP-207 should have been my first and only choice. That's ok, someone on Ebay will enjoy a 5 month old S 90ES at half price