I received a pdf file from yamaha this afternoon which was a quick guide tutorial for the Genos. One of the chapters was about compatibility with previous Tyros registrations and user styles. You can use all registrations from the Tyros 2 and after with no problems. The sounds will all work and if will pick a usable style automatically if the registrations style isn't available on the Genos.
Also, it states that if you own any Tyros purchased files from Yamaha Music Soft, there will be a new version for the Genos which will be free of charge if you had previously purchased it for your Tyros.