It's very very easy to make portraiture look like recycled garbage; I've never seen it done well by anyone in the sports industry. Lately I've been looking at a lot of fashion stuff because some of it is actually really good...and my wife is a model so its something we can do together haha.
Found a 70-200 F4L in mint condition, has always had a filter on it. Heckled the guy down from $670 (bs) to $500. Is that fair? It doesn't come with any extras.
I have the 2.8 IS and yea its heavy, but I lug it around at horse shows from 8 in the morning til 8 at night at least 5 times a week in the summer. its not that bad at all.
F4L is such a nice piece of glass, shot this outside my house, I've just been doing a bunch of tests with it to see where it vignettes, where it performs best, ect. Super stoked to actually use it for the first time, shooting some pre-season arena shit, get stoke.
You would never shoot the 70 handheld, IMO, it would have to be stabalized (glidecam/tripod/ect.), so ass long as you have a good way to stabilize it you should be fine.
It only works if you have a nice tripod. My 70-200 f4 non-IS collected dust for the first year I owned it because my Manfrotto tripod was too shitty to support it.
Either way, you have to spend about $2k, be it on a tripod or the lens.