I have the Canon 100mm 2.8L Macro IS and it does not leave my body. It's an incredible lens. Fastest, sharpest, and lightest lens I have ever owned. I made the jump from the 60mm EFS Macro to the 100mm 2.8L and the difference is incredible. The 1:1 on the 100mm is unreal, which you mentioned is what you want to use it for. Personally, I use it for all my portraiture (only thing I'm shooting digitally) and it's perfect. If you have the money, go for the 100mm, you will not regret it.