I researched cool carbons and honestly didn't like them as much as everyone else seems to. They were good, but I went with ferodo ds2500. Mine are noise free, less dusty, have more linear braking (easy to modulate), and more powerful and capable close to the limit than stock. They're a little more expensive, though: "Front pads: $224.11 Rear pads: $162.82"
Can't really speak about the "green stuff" .. I tried to look up reviews because you piqued my curiosity (I always see them advertised in like... every.. car magazine), and they get good reviews.. however 99% of the reviews are from people with cars less capable than a 300 HP BMW. Owners of everything from Minis to pickups to minivans like them... Over half the owners were truck owners!
When I go through 50 reviews and the only two sporty cars (not sports cars, even, sporty
cars) were a mini and a 2000 mustang, I'd say seriously pay another hundred bucks for a good set of pads. Your $40K BMW deserves it. If I saw at least a few more sporty car owners giving them good reviews, I'd say go for it. But... Your life may one day depend on what pads you get, and you should really match the performance of the pad with the performance of your car if you're not asking for trouble... unless you drive like a grandma.