I've been browsing Yamaha's Tyros 4 website.
The internal memory available is still minimal, and (unless I'm reading it wrong which is always a possibility) if you want to do serious voice editing and customisation you MUST install some extra flash memory.
So I've checked the price. The larger one gigabyte flash memory upgrade - the FL1024M module - costs over £200.
This seems horrifically expensive given (a) the cost of flash memory and (b) it looks like any seriously creative Tyros owner will have to fit some extra memory to use the keyboard to it's fullest capabilities. I appreciate there's some R&D cost in there but computer memory interfacing is not rocket science. This memory costs more than a netbook!
Someone please tell me I've got it wrong!