Luis, let me be a bit more precise here:
Canon source gives the AF speed spec for the 200 f/1.8 as 0.6 sec.
The 200 f/2 IS AF speed of 0.3 sec is my estimate, however, I don't think I could be off by much.
I shouldn't post anything because I have never used the 200 1.8. Rarified air for me. But even so--
Wow! Russ's pictures I think say it all. The difference in the backgound of those shots has got to be worth the price of admission, at least for those of you who are selling shots.
I sold mine about a year ago, and in that time i could have done with it maybe twice.
Like you FF is my main camera now, and F1.8 @ 200mm for portraits is getting a little silly