There are may things that need improvement in X series. A year ago, when Ketron was "pretending" to care, there was an extensive list of things that the Ketron users were not happy with. The list included features that are already implemented in SDs. For example, advance cord recognition, which supports jazzy type of playing; more location for samples or capability of making .snd files; ..etc.
But the most important thing is that many "heavy" users noticed some bugs in the OS. For example, the usage of Flash card is not very reliable; there are "hung-ups" when using aftertouch ... Those are just few that I can recall right now but I remember that there was quite few things on that list. The list was distributed to AJ hopping that something would be done about it.
It looks like the Keton has listened X users but forgot to implement the features into X series. All current improvements are focusing on SD, XD series ...which means we should buy new equipment if we want to see some of our suggestions implemented.