Trident,
I was very surprised to see 32mb's for flash memory. Hell the flash memory is bigger than the memory for the internal sounds. 32mb's is a lot of space for loading sounds.
Like Starkeeper said, the user sample area is bigger than the PSR 1500's whole sound set.
The styles as with any keyboard are subjective--this topic we've all beat to death in the past
Personally I liked more of the funk, hip hop, and R&B styles on the WK's. Even some of the basic 8 beat and 16 beat styles have a more modern groove to them.
BlkNotes, I don't think you can increase the memory above 32mb's. However you still have to consider that 32mb's is a lot of space (especially coming from a Casio keyboard). You could load a 10mb piano sample (which would blow the socks off of quite a few out there), and still have 12mb's of available space. Even just 1mb sounds will be better than the internal sounds. Especially considering if a board has say 12-16mb's for an entire sound set. You could load a huge 10mb piano, and still load 12 more 1mb sound samples. There's just so many possibilites with that amount of memory. Of course more is always better, but again cost plays in here.
I do agree that 32 note poly is still limited a bit. It appears new sounds have been added and old ones cleaned up. So if some of those sounds are bigger then poly is going down the tube
Squeak