And, I don't get the point. Doesn't the MS already play Yamaha styles? And is already a full function arranger? And can host VSTi's etc.?

Dom, how does the MS deal with the 'floating' CPU requirements, depending on how intensive the VSTi's you use (and how hard you use them)?

Can you set a preset limit for polyphony, and how does it deal with notes over the limit, etc.? Does latency remain fixed, and polyphony change due to CPU load, or does it balance a heavier VSTi with a higher latency?