I think it all comes down to wants needs and dollars. First let me say that if the E92 M3 were available when I got my 335i coupe, I wouldn't have ordered one. Not that I don't think it is not a great car, but for a daily driver, the 335i is a better car. Less expensive, better gas mileage, great performance, that can be made even better with a Procede mod. If I were ONLY interested in tracking the, the M3 would definitely be the way to go. Also, if you just WANT to have the latest, greatest, biggest and baddest, then the M3 is also the choice. Since I don't track the car, I don't need the V8. I just sold my V8 S4 and am glad not to visit the gas station so frequently.
Both cars are great but have different purposes and advantages and disadvantages. To me the extra money paid for the M3 is not justified. I'm sure for others there is justification. I can live with that.