The beauty of the "L" lens is its fast AF and its IS when you want to hand hold your rig.
A really serious Macro Photographer is going to use a tripod, and IS is of little value then.
I'm a non serious Macro photographer who likes to photograph whatever I see while I'm out walking around. I'm the type of person the 100L was made for
Here are some hand held shots. Not in the same ball park as serious macro shots, however, I can take good images without a big setup. My first priority would be getting better lighting, most of these are just ambient light, but the June beetle had a flash on the camera.
On my Raspberry bushes:
10 lined June Beetle