Sheldon N wrote in post #10293174
I'll be a slight contrary voice here. I had a 200 f/1.8 L for a while, and while it was phenomenal I found that it wasn't a magic solution to anything. Plus it was stinking big and heavy! I found that the combo of a 70-200 2.8 IS II plus a 135L gave me a more real world flexible shooting kit. Shallow DOF from the 135 if I need it, flexibility with the zoom for other situations. The difference between f/2 and f/2.8 isn't that big, but the difference in lens diameter and lens weight between a 70-200 2.8 IS and a 200 f/2 is. For me, the 200 1.8 was big enough that it was a specialized lens that I had to plan to take out and shoot. A 70-200 can be tossed in an over the shoulder bag and then I'm out the door.
Most of the really stellar shots I've seen from the 200 f/2 were stellar shots regardless of whether they had been shot at f/2 or f/2.8 - good light, good composition, good subject, good photographers. People who really know their stuff photographically can see the difference, but your average viewer would have a heck of a time sorting out a pile of 135L, 70-200 IS II and 200 f/2 shots taken wide open by the same photographer.
However, if buying the 200 f/2 is enough to satisfy the inner craving inside you - then do it!
On this forum there was a comparison @f2.8 between 70-200L2.8II and 200L2.0@F2.8 .... it was very easy to see the difference ..bokeh was smoother and blur was comming quicker and much more regularly with the 200L2.0 ... and we even don't speak when light is falling down, it's a big step between F2.8 and F2.0 ...
I own a 135L2.0, I was very pleased with it but after I bought a 300L2.8nonis for motor sport.. I surprised that contrast and sharpness are so different .. We can see straight away with which lens the picture picture was taken.. Actually I prefer to carry 3kg and be a bit far from pilots then use the very light 135L2.0 even if distance is really accurate with it. Bokeh, contrast and sharpness are much more spectaculer with it, as I can see which of my pictures has got the favor of pilots (for quadbike races). I use the 135L2.0 only when I don't have enough place. If I could afford it, of course I would change my 300L2.8nonIS for the near to perfect 200L2.0..
But what is true, is when a very good photograph takes a pictures, he knows how to manipulate more important parameters like light direction, appopriate DOF, best distance lens/subject/backgroundunder to get a nice smooth bokeh, exposure or over exposure to saturate colors, etc etc .... so even with a non L series he will get consistant series of pictures.
For common photograph (like me), it takes more time for every picture and luck will be also more or less a part of the quality of the picture.
But nobody can say that a 70-200LMKII gives same result as 200L2.0 .. you can see directly the difference between the two lenses in one second. Or you should buy or change eye glasses 
It's like a 85L on crack
