I ultimately elected to go with the Canon EF 70-200 f/4 L IS. The Canon EF 70-200 f/2.8 L IS may be a slightly faster lens, but I can’t justify almost double the price (and weight!) for that 1 stop.
I tested this lens out today in the backyard, mostly hand held… and I was quite happy with its performance. I have other lenses that I consider to be good quality optically but this one was pretty fantastic (even if some of my shots weren’t 😉 ).
Black Capped Chickadee (Poecile atricapillus). Second picture is a 100% crop of the first. This was an experiment, I realize the larger version is a bad photo.
I’m impressed!