Very nice indeed
I also tried macro with a 5D2. Didn't matter too much having the shorter working distance. If you can get close enough to fill the frame with a 1.6x crop it's not much more effor to get a bit closer and fill a full frame. The big issue I had was the big loss in depth of field compared to the 1.6x crop which is why I didn't buy one and got a 50D instead. I did think it's be pretty sweet with a shorter lens (100 compared to my 150) as it compensates a little for the loss of depth of field by having a slower drop off from in focus to out of focus. The Canon L with it's IS is phenominal and I've sat alongside a guy happily shooting with that when I can't get anything sharp on my sigma 150 on a monopod late in the eveniong.
I'm very tempted to get rid of my 70-200 that I rarely use and get that canon 100!