I'd argue that...the 135 f2 and 100 Macro L are so similar I've yet to meet anybody that can reliably distinguish between images shot with either.
Which of those two lenses do you think was used for this shot?
Er the 600 with a 1.4
I didn't word that very well did I? Nothing new there. What I meant was if you have the 17 TS-E and a 1.4 TC there is very little practical need for a 24 TS-E, and if you have the 100 L Macro there is little practical need for the 135 f2.
As you, I do a lot of research before buying a lens after deciding I need one, I travel a lot so whilst having one of everything might be a nice idea (principally to a collector ) it is generally impractical. My research, specifically with regards actual resultant images, pointed me to get the 17TS-E (and a 1.4 TC) and the 100L Macro, even though I shot with a 135 f2 for many years in the manual focus FD system.