Stephen.
This link might be of interest:
http://www.nnplus.de/macro/Macro100E.html
Also see the review on
www.PhotoZone.de.
I used to own the 105mm F2.8 AFD, but I never liked it. The Bokeh was very ugly, but otherwise I cannot really say why I did not like it. It is not IF unlike the new one.
By all accounts the Tamron 90mm F2.8 lens is better than the old Nikon. In your place I would opt for the Tamron unless you need the slightly more robust Nikon build, or the VR feature. Note that the VR feature is not very effective for close ups, but of course will work for portraits etc.
The general concensus is that optically the new one is a little bit better than the old one.
www.NikonCafe.com has a recent thread on this in the "lens lust" forum.