Howdy. It sounds to me like you really need to do a lot more thinking about your choice before making a sizeable expenditure such as a new M3.
As far as looks go beauty is certainly in the eye of the beholder. That being said I can pretty much guarantee that as soon the the E92 M3 comes out the E46 M3 will look dated and less aggressive. Sure folks have their reservations now on looks, but that is just part of the process. Next if you are the type of person who just has to have the latest greatest keep that in mind, even if you are not sold on the looks yet. You will likely end up with regrets after you see the new car on the street or next to your E46 M3. Performance wise this is a no brainer. The new car will really be a huge step up and not just in acceleration and top speed. Most of us expect the car to totally "envelope" the E46 M3 in all areas of performance.
SMG vs. 6MT
SMG is superior for track use. No human can match the rev matched downshifts nor the sheer speed of the shifts with SMG. No way to mis-shift is a nice bonus as is a pseudo automatic transmission mode. The only arguments I see for 6MT are reliability/simplicity, a tiny bit of weight and a desire to be more "in touch" with the shifting process. IMO though, the SMG allows you to be more in touch with more aspects of spirited or track driving i.e. less in touch with the mechanics of shifting and more in touch with the WHOLE car. You can focus more on acceleration, braking and cornering and less on heel and toe-ing.
Hope this helps.