I used to have an 03 e46 M3 and loved it....this on is even more fun. Exhaust is a tad quiet. I cut the resonators from the 5 and it made a dramatic difference. I am contemplating removing them from the roadster but I have a feeling that my wife would object as it "her car" LOL.
Congrats! I've driven these a lot and they are a lot of fun. Great choice to pick this over a Boxster S. The Boxter is a nice car, but very little comes standard and they are far more expensive than M roadsters from similar years.
Gorgeous -- congrats on the new purchase! Z4M will most probably be more fun on account of it being MT unless your M5 is also MT? Either way, best choice on all parts, they are both super quick and both can be used as DDs. All thats left for you now is a 4x4 truck and then you've got all a man needs in life.