I, sir have beaten Crysis 2 on SS, and it was less than epic. People that have played the alpha have said that Their experiences with BF3 was that it was less demanding than people are trying to make it out to be. I happen to have high hopes for BF3's SP as well as MP. Dont try and dismiss me as invalid because I differ in opinion from you. And please dont flood the thread with multiple posts.... there is a such thing as an Edit button.
You are going off the way it LOOKS without any real proof of how it will run. What type of DX11 features are active? how much AA? those are the things you need to find out before assuming something will run like another because thats just rediculous to say " they look kind of similar, so im going to tell someone that they will run the same"
X heavy has the correct idea on how to build a system with the most demanding game out in mind, although a bit overkill.