Thanks for the clarification. I thought the M3 was more like 4.3 but either way, knowing it replace the "is" makes more sense, though IMO just makes it more confusing, we all knew what the is was.
Re: the s4 competition though, isn't that already the 335? I would expect the M335i to beat the S4 not match it, and cost more. Basically creates a 4th segment that Audi doesn't compete in ( nor anyone else), which certainly isn't a bad thing for us...