I ended up with the 120APO, although I was originally eyeing up the 100.
Not sure if it was the best choice. I'm still considering if I should pickup the 100 as well, but don't really want to spend the money on lenses that are so close in FL (I also have the 70mm).
My take on the 120APO if it helps. I found it a bit boring at first, but have grown to like it's subtle nature. The bokeh is good though slightly plastic. The falloff can be a bit weird, but the sharpness and colors are good.
From the two times I tested the 100, I couldn't get any shots in critical focus. Perhaps it was my technique. Perhaps the lenses I tested were bad. Either way, in both cases I was left wondering if it was me, or the lens. Which isn't a good sign, as most of the time, it's the lens. Especially considering every other lens I tested on the second time out ended up sharp and accurate.
The thing that keeps me interested in the lens is the final results. I see some great images made with the lens. I really do like the quality and speed. I kinda wish that the 45 was a Summicron as well. 100/45 summicrons would make a great two lens kit.