Oh so you bought the one from Jack Daniels. I called on this car and they said it was "sold" but some work was being performed to it. Such a clean car. Congrats!
I was in the exact same boat as you. I wanted to trade my m3 for a 996 gt3 as there was a limited production run on these cars and the history on them is amazing. I went to test drive one in Conn. My overall driving impression was this car felt much more raw and definitely more planted. I was totally impressed with the driver/car connection, its really amazing. I believe that the lack of electronics makes this possible.
However, in comparing the two I felt it just was not worth the trade on the m3 because:
1. Performance feels very similar against the m3 obviously due to the high rev characteristics. You do loose a ton of the electronics and comfort items that you get in the m3. However, these also do make the character of the Porsche.
2. I grew to dislike the lights on the 996 more and more as time went on. I started off not really caring about it but as I looked at 997's, the headlights began to bother me.
Last week I called the salesman and told him I was no longer interested in the car. My goal was to pick the car up tomorrow (my birthday) in which they were giving me great trade value on the m3 as well. It was a really tough choice to make.
If I was in the position to keep both cars I would without a question buy the 996 GT3. However as a trade, the m3 is just too good a car to trade against it in my opinion.
My goal is to keep the m3 and get 997 gt3 as soon as I can.
Good luck with the car and I know you are totally going to enjoy it. I've done a ton of research on this car and there is nothing but good out there, especially on the legendary metzler engine.