I have often contemplated what would make me take the plunge and “update”. I do not have an answer. (!!???!!) largely because the things that I am use to and love may well not be present in the update, and change is always difficult, especially if you have to compromise on what you already have. I guess there will always be trade-offs (read disappointments) on every change. (However I did not really have too many (!?!) disappointments when I moved from the PSR 640 to the 9000PRO.) It’s a pity that there is not some generic standard of features (apart from the very basic ones that exist) that evolves which could include things, apart from the normal hardware configuration, that are more software functionality - like the number of variations, fills, harmony, eq mixing etc. You know, the things that we often take for granted, (because we often already have them) until we find out that it’s not, it’s only half the measure. Such a generic standard of features would be “make and model independent”, and could grow and evolve with time , and it would become the yardstick for every new model that was released. The standard would be referenced by time only. So when for example Roland releases the replacement, it is manufactured to at least the “standard” and one can quickly refer to the standard and see just how the new model supports it and where it improves on it, or falls short on it.
Anyway that's my two pence worth.

Jon.