Well, besides the increase in ram memory I’ve found 2 other differences.
Registration memory can now save and store both “transpose” and also
“live control”.
Jim
The PSRs could always save transpose in registration memory. However, adding Live Control to registration memory opens up new possibilities for live play.
I've owned the PSR-740, 2000, 2100, 3000, S900, S910, S950, S970. For the first time in 20 years, I'm going to skip and wait what will probably be two or three years for what I hope will be a blockbuster.
I know that if I did upgrade, absolutely no one in my audience would hear a smidgen of a difference. If the new keyboard was packed with Tyros 4 voices, I would hear some positive comments.