I've got it, and also a 75-300 IS (yeah, the old one.) I haven't used the 75-300 since getting the 70-200, because after looking at the results of the new lens, and then looking at some older pics done with the 75-300, I could barely call any keepers. That said, the new 70-300 is supposed to have much better IQ than the 75-300, and mine has taken some abuse, possibly making it worse than average.
The 70-200 f/4 is a very nice lens for what it is. It's great in bright light, and good for outdoor sports (or other fast moving things.) when the f/2.8 is out of your budget. If you use a tripod for most of your telephoto work, then you won't miss the IS at all.
I do miss the IS. I'll probably get the 100-400 someday to get a good compromise. I definitely plan to keep the 70-200 though.
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3oD, Fifty f/one.eight, twenty8-1o5 f/three.five-four.five, Seventy-2hundred f/fourL