David,
thanks for the reply,
maybe that's the problem, i really don't understand the reason for the change, that is indeed my initial question. (is it much better? is digital piano dead-end? will it lead to inability to improve my piano skills at some level (when?!))
given that, should i upgrade or not? 
The difference can be profound. The key word there is "can". It can also be profound in a negative way, just depends on your view, the size and condition of the piano and quality level of the piano you buy into. To some people both are almost a requirement ( a digital as well as an acoustic).
What you need to do is get out and play on some acoustics ( always fun to try out pianos) and get a feel for yourself if it's something you are interested in. It could be that you find out you don't want one or it could be that you feel you have to have one.
Now assuming a reasonable size and not a so called spinet or console piano is bought then you can expect a seriously more resonating piano, especially the bass. And when you play something that should have a longing or dissonant sound to it a good acoustic can't be beat.
You have a decent piano now, take your time.
David