Hello Rikki
The software is not being shipped until November, so the only information is as you see on the site, however talking to Wersi at the Pakefield festival, apparently the style system used for the Yamaha styles has been licensed from Yamaha, and is an addition to the upgraded Wersi Style System, but is also fully integrated into it, so I can only presume that all the Yamaha sound maps have been incorporated into the software, as to what voices are used we will have to wait and see, although you will be able to edit them just like any other style. (From the way Wersi was talking at Pakefield, I also got the impression that they are also in negotiation with other manufactures)
Whichever way it is done it certainly looks interesting

Bill