Mark Sturtevant wrote:
It is strange to me to see all the posts saying that this [major brand macro] is the way to go. The differences in image quality between a Nikon macro and, say, a Tamron of similar focal length will be so slight that I doubt you would see the difference. But you will see a difference in the pocket book. The point is, it is hard to go wrong with these lenses.
Optically, the differences are negligible. Where they come in are in added features, build quality & resale value.