1. For the functions, and lots of 'em. Fancied a change from a PSR-S770 within a similar price range of approx two years' ago. Like the multiple connections together with the powerful speakers, able to connect other stuff to the keyboard's amplifier and make high quality recordings of inputs. Like the shape and colour, looks like no other keyboard.
2. 16 PADS a big draw, velocity sensitive, make own audio samples.
4. Availability (UK): Negative, but that didn't stop me from buying mail order from Germany. No UK shops stocking Casio MZ-X500 and got cold-shouldered by UK dealers when trying to order one. So ha-ha to UK dealers with their heads stuck up their own *****.
6. Yes, I agree, it is a rare and original model from Casio. Does me nicely.