I would adore a 6 octave S900, 700 or 500.

Had I not read bad stories about the 9000Pro's processing problems I might well have picked up a second hand one rather than my PSR3000.

To my mind [not] creating such a keyboard looks like a market deliniation issue, I agree with the theory that making a 6 octave mid-range arranger could well impact other sales.

Lets face it, Yamaha already make 88 key arrangers in the CVP range, seemingly based very heavily on PSR 1500 and later hardware. They make bearable (to some of us anyway) lightweight 6 and 7 octave keybeds used in the DGX range and the NP30 piano. Putting a 6 octave keybed onto a CVP eletronics board is damn near just a case of getting around the "some keyboard matrix connections aren't in use" issue, so I don't think it would cost Yamaha that much time, effort and investment to put S900 electronics into a DGX 6 octave shell.

Therefore it's a marketing issue!