I'll answer the OS question and let RadioBox add his comments.
OSX is currently 1 unit peer to peer. It is the new driver technology that proves to be very stable and is device aware meaning it knows the device and connects it, names the I/o and properly reports it to ASIO for connection to/from DAWs.
Windows XP/Vista is Multiple unit driver and is the first network driver based on the new code. and is device aware of the new Yamaha devices (n series and Motif XS) It too is much more robust than drivers we have seen in the past
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Feel free to ask me any technical questions. As for opinions.. that's for you guys.. I'm biased..