Well now here's a different thought on this subject...
I own a KN920 and play publicly - the machine does everything I need it to, with a bit of amplification...and the quality of the sounds and rhythms is unsurpassed in my view.
What I am constantly looking for - either free or to buy - is style files for specific songs, as I do like to make my performances as realistic as possible.
Sure there are fancier gimmicks on the newer machines but what I focus on is entertaining the audience to the best of my ability rather than some more toys to play with at home...
Roger M