all depends how far away you are.... the 7d has the 1.6 crop factor so for distance will boost your 70-200 to a max of 320mm... 5dmk2 no crop factor, so that'd be the decision maker for me.
i do hope that visitors of this forum realise that crop factor does not mean one can multiply crop factor with focal lenght of lens. 55mm is 55mm regardless of crop factor. so when 200 mm is put on 1.6 crop factor camera image is no closer, just croped because it is being projected on smaller sensor, so more detail is being lost then on ff sensor. that means 200 mm on 1.6 crop sensor is still 200mm lens. it will never become 320mm because it does not zoom in more, it just crops image.
As long as you work under good light conditions and the higher light gathering capability of a FF sensor can be neglected (from what I have seen on the 7d up to maybe ISO 1250) the camera stays competitive to a 5d MKII as the 7d acts like a (theoretical) 18MP x 1.6^2 = 46MP FF camera for the croped part if would be scaled up to FF sensor. The question I would be more concerned here is with the theoretical limit of lenses if it really comes down to this. if higher ISO capabilities become important that is of course another story ...
However in reality I guess few ppl look at pictures this way, so I guess the 1.6 magnification that the 7d delivers is good enough for most persons who just want to have a longer Telephoto range for eg occasional wildlife without spending a fortune on a 500, 600 or 800mm lens
but there is noooo magnification whatsoever. none.
The best way to think of it (for those who ever used crappy digital PS cameras)... it's like digital zoom... it will crop the image so it appears to be closer but really isn't... in all reality. The lens doesn't magically get extra elements and magnify an image just because it senses it's on a crop camera... It outputs the exact same info it would send to ANY camera but depending on if the camera see's all of the info or not will depending on how the camera "sees" the image.
Also keep in mind given the high density of the 7D, it can produce stunning images but it will require stunning lenses. If you use the 7D with the kit lens 28-135 at high ISO, it's going to look like crap. If you use the 7D with L primes at high ISO, it will yield more usable images. At then end of the day, I still say between the two, get the 7D or 60D, get some awesome glass, and then later if the 5d m3 comes out, then all means sell the 7D and get it. Glass will be as big if not bigger factor in overall image than the camera will be in most situations.