There are quite a few artists that play Wersi, and most of them tend to use the organ variants, however as there is no difference in the sound from the small Ikarus to the large Lourve, listening to any will show you some of there capabilities.(Manuals, Pedals, Layers and cabinets are the most differences)
http://www.wersi.net/LambertLIVE_small.wmv is one short video of a professional European player. (Using just OAS 6 voices)
I will try and find some more.

Spalding
My friend has a lot of VSTs and Akai samples on his Scala, and when he returns from holiday I will see if I can get him to do some demos, as you requested.
BTW The sounds of OAS 7 easily equal and in most cases better a lot of the Akai samples that are available, so if you do a search for quality Akai sample demos, you will have an idea of the sounds that OAS 7 can produce.
Hope this helps.

Bill