I stumbled upon your samples on flickr and followed the link to this thread. Also I've read here for quite a while, this answer gave me the final reason to register.
Ok, so what I like to point out is that the performance of the 180mm as demonstrated by you differs from my own experience. I've shot some sports events with it, mainly soccer, on my former D80. I happen to have had the 105mm Micro VR on my D80 as well, but never at the same time. Although the Micro is sharper at 2.8, the 180mm is much sharper than displayed in you samples.
However, when I read that you took the photos from a short (albeit not for a macro) distance, it somehow explains this variance. I myself noticed, that the AF tends to front-focus at closer distances. If you used the AF, than the performance is obviously due to a front focus error. The appearance of the blur supports this theory, I think.
Like him or not, but Mr. Rockwell noticed this a few years ago as well and I could confirm his findings:
"On my F100 there is a little AF error at closer than about 40 feet. AF is fine beyond 40 feet. However, if your subject is closer than 40 feet the camera tends to focus a little bit closer than it should, lowering sharpness when shooting at f/2.8."
This was never an issue for me as on a soccerfield, the players usually are acting at quite a distance.
PS: In case you still want to sell the 180mm, I would be happy to get a quote, including shipping within germany