IDK, I was often thinking of selling my 70-200/2.8 for the f/4 IS since I almost never use it at f/2.8 anyway. Then decided that since my 70-200 is so old - it's the first IS version, and has suffered innumerable repairs over the 16.5 years of service - I would not be able to sell it anyway (short of giving it away for free), so I'd rather not complain about the weight and just carry on shootin'. 
It still does perform well even on a high-MP full frame body, need I point out (I think it wasn't tested on FF here... was it?)
It still does perform well even on a high-MP full frame body, need I point out (I think it wasn't tested on FF here... was it?)