My experience is similar to other's.
You get a basic level of compatibility (yes, old styles will work), but need to do a fair bit of work to really exploit and use the new keyboard. This includes tweaking volumes, voices, ya-da, as other folks have mentioned. I've played my pop repertoire book from cover to cover many times, making tweaks along the way. Even after a few years, I still find a few divots to fix.
This is one reason why I don't automatically jump to the next shiny object. I went from S950 to Genos, and intend to stay at Genos (mk1) for a long time to come.
All the best -- pj