Whilst the good folk of Fixation were repairing my camera yesterday, I had a play with the new Canon 200mm f2.
Totally unscientific and
very limited testing but it's a lovely bit of kit

.
Physically similar to the 300 f2.8 but a bit shorter and arguably much more comfortable to handhold. I did have a chance to have a go on one of the famous 200 f1.8's a couple of years ago but found that heavy and really nose heavy to boot. This new one is a much better balance (on a 1D series body).
The 4 stops IS certainly looked to do the job with an acceptable 1/15th shot.
Sorry I don't have any pics but the chap who runs
The Digital Picture has some crackers.
Unfortunately the £4K+ price is a joke

though, and I'd still think long and hard if it was £2.5K. I was quite close to hiring it for a while but decided that the £150+ for a week wasn't money well spent, as I don't have much planned for
this week.
Having recently used a 500mm f4, 300 f2.8 and this, I'd say the 300 is the most versatile for what I do, the 500 the most fun and the 200 probably the most specialist.
Just need to try a 400 f2.8.....