DO you agree the two lenses are pretty similar but with 100 being more verstile?
I do not own 100/2.8L but I own 70-200/2.8L IS II and 135/2L. 100/2.8L cannot do f2 and focuses slower. Yeah, IS is nice if you shoot something static, like NOT people. I had 70-200/2.8L IS II first, but I wanted bigger aperture, I'm very happy about the bokeh and shallow DOF of 135/2L which f2.8 can't offer. I would say, that id you want macro, buy 100L, if you don't need it, buy 135L