By the way, in the real world things go in a different way. The pixel quality of the 5D MkII is in an other league, and the best you can obtain by the 7D+100-400 is very similar to the same image cropped on the 5D MkII...I found the 7D an overestimated camera...
Based on some previous empirical testing, comparing the same test scene shot with a 7D and 5DII, with the images from the latter cropped to the 1.6x FOV (resulting in an 8 MP image from the 5DII), the outcome boiled down to the 7D delivering images that were a bit sharper but a bit noisier than the 5DII.
The other issues are AF - for fast moving subjects, even if the pixel-level IQ is similar, if the 5DII's AF system can't lock on and hold, the resulting images will be useless. Likewise, the faster shutter and shorter shutter lag and VF blackout duration on the 7D can help get shots the 5DII would miss.
Thus, I think the 7D and 5DII complement each other very well. Yes, you can shoot action/wildlife with a 5DII, and portraits and landscapes with a 7D, but neither use is a strong point of those bodies. I'm a firm believer in using the right tool for the job at hand.