To me; the 135L seems like a bother but every time seeing the images it brings to mind that old saying that 9 women can't make a baby in a month. Likewise; 2000 good images don't make one great one. Somehow; the 135L makes the great ones way more often than any other L I've had the pleasure of using.
For macro photography; the same can probably be said of the 100. I'd love to have that one too.
I like this analogy too. I actually used both for my Christmas photos of the kids (for head/shoulder shots) opening presents and every time I had a shot that just looked like I really nailed it and I thought WOW that came out nicely, it was with the 135L.