I did some fiddling with my Nikkor macros - and I have some exotics, like macro lenses made to be mounted on bellows and only 1:1 and closer - but the whole non-m4/3 drill of stop down metering and open up to focus then stop down made me crazy.
The panny/leica 45mm macro is great. The only downside is that I've developed a style over the years with my Nikon gear that was hugely stopped down for maximum DOF, and with fast shutter speed, hugely stopped down, and flash, allowed me to isolate subjects at mid day like they were shot in black studio backgrounds. Well, with m4/3, you can't stop all the way down and get reasonable (meaning, you can fix it with unsharp mask) sharpness. I have some ladybug images as close as I could focus the 45mm macro, and in order to have enough DOF to shoot and get the whole ladybug in focus plus just enough of the surround to give some context, I lost way too much sharpness to diffraction.
It is what it is. Great macro lens, just not the right tool for hugely stopped down images.