That's right, only the 135L could deliver that image on this particular cropped camera image! this even shows how good this lens is on crop cameras! No other lens could because no other lens is 135mm f/2 that melts the background like that with compression like that.
Your the one who said, blah blah blah "I could do that same shot from your crop camera on my FF camera with a 70-200II 2.8 blah blah blah" this mentality is completely wrong and stupid. You simply cannot accept that the 135L is a better portrait lens than the 100L, which BTW I never stated was bad but just not as good.
You have to be some sorta measuabator who has yet to post any real photos on this thread. You forget that the artist chooses his tool because the artist can tell between them. I can see a visual difference in the shots I've made with the 100L and the 135L both wide open. The 135L I found superior for portraits.
You say you can't tell the difference well good for you. I'm sure your happy with f2.8 and could argue that you wouldn't see a difference between 2.8 and f/4. Then you will say there is and I will say they're isn't. It's after all! Only one stop.
I've gave my experiences and opinions based on using both the 100L and 135L and I've even added some examples lying around my hard drive. Why you yourself have done little for the original OP except waste your time preaching to the choir who's shot on crop and FF cameras both lenses.