I think the "theoretical" performance comparisons are being done because those are the facts at the moment. Since few people here have actually driven the car, it kind of makes it hard to talk about how fast it really is, or how fun it is to track. Since BMW includes the Porsche, Audi, and Mercedes in their own brochures for the M3 as comparison, is it unreasonable that people would look at the same cars?
But then again, you already know (how, I can't imagine) the M3 will be fast and fun to track. So instead of complaining about the people doing "theoretical" performance comparisons, why don't you start a theoretical thread on how fast and fun to track it is. Oh, but that would be silly at this point...
