I am not a Ketron user, but still want to chime in on this discussion.
I did see many promotional materials about X-1, which were all very explicit in heralding non-obsolescencse. They were touting it as the feature which would set the X1 apart from the competition. Whatever experience we have had with other brands does not apply to Ketron if thet is how they positioned themselves.
Even if they had not advertize their instrument this way, they are still obligated to provide critical fixes to the OS (and granted, they have done some of that). But as long as there are other outstanding stability problems, Ketron MUST address those (even if it is past the warranty period of the instrument). I believe this is the consumer law in most states in the US.
As far as changes that would be considered straight enhancements: a number of other companies had provided those to the users for free, without any apparent necessity (e.g. Korg PA80 Ver 3, and Ketron's own SD1 Ver 4). It is not unfair for the other Ketron users, sold on the concept of non-obsolescense, to expect similar treatment. However, I am sure that even if Ketron wanted to charge each user a reasonable fee (I'd pay up to $100, or maybe even more, depending on what was in the upgrade), this would still be preferrable to getting rid of the instrument one is used to.
Just my $.02.