You're right. According to the benchmarks, they trade punches depending on the game. http://www.anandtech.com/bench/product/1037?vs=1041
Personally, I'd take the Nvidia card by a slight margin only because I like the NCP better than CCC. And I like having PhysX. Plus the new GeForce Experience is great for optimizing your games if you don't like doing it manually. But I wouldn't toss either card out of my PC.