100 2.8L IS Macro vs. 135 2.0L for handheld portraits

Thanks all for the thoughtful replies! I wouldn't say I'm closer to a decision though

I currently own the 85 1.8 and the 70-300 4-5.6 IS USM.

The macro abilities and IS of the 100L are appealing, though it is somewhat close in focal length to my 85. The 135, with it's aperture and potential use for the occasional inside sports I shoot, would no doubt be a winner as well. I don't think I can go wrong!