This is what you are looking for when his site comes back up...
Yes, I've seen those before. But what really is the take-away from that? What are the practical implications? Clearly, you don't want to use anything under 50mm for head shots. We kind of knew that already but this series makes it even more clear. And yes, even 50 through 85 can be borderline depending on the model. But seriously, what is the difference between 135 and 200 or higher here? If you shuffle those samples around or just show real life samples I bet most of us wouldn't be able to tell what was shot with a 100L, 135L or 200L. They all work for this really well and it becomes more a question of other factors that you may prefer or not. Distance to the subject and type of location being the more important ones here I think.
Those are wonderful but that's not the question. My argument is more that those could be taken by a person with that eye and talent for locations and lighting with a 200 or a 135 - and probably a bunch of other stuff. Just by looking at those I really have no clue as to what they were shot with. I've seen pretty similar shots that were done with the 50L or 85L. The difference in perspective at the longer end is not that obvious. And with regard to the OP what I meant to say is that it more depends on your style and how and where you like to work to decide between those two fabulous lenses - with the focal length being the most important factor.
The photographer explains why those shots have the 200mm/2 look to them and how the 135L doesn't quite match up to it.