^ Good post devo. I knew you would be first to reply!
My two cents are short and sweet as well. One of my principal arguments in favor of the M3 is based on price to performance ratio. The cars are in fact very close in most performance metrics. Have a look at the list on this
page (or the latest master list in the same thread). It seems to me that you already understand the strengths and weaknesses of each car quite well. When the cars are so close in price, or maybe even slightly in favor of the Porsche in your country, the decision does become very tough. Even though both cars are quite capable both on the track and as a daily driver the 911 leans a bit more toward the side of the pure sports car for the track and the M3 a bit more toward the GT/very fast daily driver. I think the versatility, comfort, engine and DCT (not in that particular order) are the factors that still give the M3 a slight edge in my opinion, even at these prices.
Good post and best of luck on your difficult decision.