Just my twopenny worth - I agree with Ned in as much as it is naive to expect a manufacturer to deliver "non-obsolesence". Where would their future sales come from??
However, I think that upgrades should appear that address bugs or shortcoming to the advertised specification.
I have played Ketron and Solton a long time now and anxiously awaited additional memory for the MS40 for many years so that I could have more than 4 or 5 user styles loaded before realising that this vague promise wasn't ever going to be realised. If you look on the net at the Yahoo MS40 group they are still going on about it.
No - you need to be satisfied that what you buy is what you get at the time - I swapped up to the XD3 and should have changed years ago. Although Yamaha have issued upgraded OS for different models these were mainly to fix early release bugs just like Ketron did with both the X1 and the XD9 so what's the difference.
If you are dissatisfied with the product then vote with your wallet. I have now tried the Tyros, and the Technics 7000 along with lots of earlier models and I'd rather have what I have than anything else (well perhaps the Tyros if it wasn't so overpriced although I still find the drums a bit insipid and I can't find a GEM to try)
Only my humble opinion of course
Regards - KF