Terry,
For serious recording, one needs to have 120 Gigs. I recently replaced my 30GIGs audio harddrive with 120 Gigs. I do not believe the intention of Genesys to replace our own dedicated software sequencers and hard drive recorders. The intention is to allow us to create quick songs on the fly.
For example, so many times, my church asks me for a quick selection of songs Sunday morning. So I may have only on hour to do multiple songs. The genesys will allow me to do these songs very quickly, put them on a cd and erase them from the harddrive. Many of the friends of my mother come to me asking that their kids sing while I play for them. They want their kids recorded. Usually, I say NO because it is too much work and time consuming. With this, I can generate the CD, give it to the mother, erase the files from harddrive. Finally, So many times I get very nice ideas that I wish I can record. However, because it is time consuming to record on my dedicated studio, I simply do not do it and I lose the idea very quickly.
Concerning th 64 polyphony, I agree with you. However, I have sk880user with 64 polyphony and I have never ran out of polyphony and my sequences are very thick with many instruments. Also, I have a bad habit of overusing the sustain padel and my music teachers always told me about it.

I believe there is something true about real-polyphony... because with other keyboards I easily run with 64 polyphony but not SK880. Remember how some sounds take more than one polyphony? Well, if in genesys, one sound is one polyphony, that can be very good.
Finally, the street price of Genesys is $3000, this is what I paid for SK880PS oriental fully loaded with all options (except scsi). I agree that 5K is not a reasonable price but I do not believe any dealer is selling it for that outrageous price.