Disklavier

I think athomik makes a good point. I recently puchased a MKIV and am 
far from a professional piano player and using it as a high end 
entertainment system - well at least until my piano skills improve! 
(As a side note, it gets about 8 hours continuous play each day and 
offering outstanding return on investment if you measure it in terms 
of hours played /$ spent)

To me, upgrading the HDD is a drastic option, even if it is 
technically feasible. Someone earlier indicated that plugging a 
storage device via say USB would not be possible for playback. At 
first glance, there seems to be no obvious reason why this should not 
be possible and is likely to be a software/firmware constraint.

As we see technology moving into an era where the HDD as we know it 
will be superceded by solid state memory devices - at least until 
network speeds increase reliably to enable remote storage elsewhere on 
a network or internet - USB-accessed storage media seems to be the 
least invasive, cheapest and most flexible option for Yamaha to 
develop.