Anyone having the Leica Lumix DG Macro-Elmarit 45mm are likely to be using larger apertures than f/5.6 for non macro images. I have also made a comparison of the bokeh rendering for larger apertures for this lens, and a bokeh comparison with the Olympus Zuiko Digital 50mm f/2 macro.
All the images were taken within less than five minutes, and the lightning is hopefully pretty similar for all of them. I did not use any filters on the lenses. The camera used was the Panasonic Lumix GH1.
One situation which is commonly difficult to handle in terms of bokeh, is foliage, especially when hit by direct light. So I put foliage in the background. The lens was focused to about 1 meter, which is the closest focusing distance of the Lumix 45-200mm. The Lumix 14-140mm focuses down to 0.5 meter, while the 45mm macro, being a macro, of course focuses much closer.
This distance corresponds to taking a close head portrait at 45mm, which is one of the situations when you may be worried about the bokeh of the background. The background leaves are about 5 meters from the camera.
Here are the full images, all taken at 45mm, f/5.6, ISO 100, one meter focus distance. They were scaled down, but not processed in any way beyond that.
When looking at the full images, they look pretty similar. However, let's zoom in on some of the details. Here are 100% crops of the centre from all three lenses (click on the image to see an enlarged version):
In this picture, the Lumix 14-140mm has the least pleasing bokeh. The bokeh for this superzoom lens is "dirty" and "swirly".
The flare also appears to be more pronounced for the superzoom lens, as is visible in the lower left corner. This is probably due to the more complicated construction of the superzoom lens. After all, the superzoom lens has 17 elements, as compared with 16 elements for the 45-200mm, and 14 elements for the 45mm macro. More lens elements usually means more stray reflection inside the lens, giving flare when there is a strong light source in the front of the lens.
The other other lenses are pretty similar in terms of bokeh. The bokeh is completely adequate, even if they do display a bit of ringing around the highlights.
Let's look at 100% crops from the upper right corner area.
In the corner, I think the 45mm macro is a tad bit better than the 45-200mm. And they are both much better than the 14-140mm.
Finally, a crop from the lower middle area:
There is hardly anything surprising in this study. The Panasonic Lumix G HD 14-140mm is a superzoom lens, and not optimized for bokeh. It has a small maximum aperture, and you're not going to see much bokeh in your pictures anyway.
The value tele zoom Panasonic Lumix G 45-200mm has a pretty nice bokeh for such a lens. I would say you could use this lens as a portrait lens, given that you mind the background a bit.
The Leica Lumix DG Macro-Elmarit 45mm has probably got the best bokeh among the three, but I would have expected that it fared better compared with the zoom lenses. Most people would probably prefer using a smaller aperture for portrait distances with this lens. I have made a comparison of the bokeh for smaller apertures as well.