I have both the D and the G. I cannot see that the G is sharper than the D. On an informal basis they both seem equally sharp to me with the old D maybe have an edge over the G for some shots. Can't believe everything you read, gotta test for yourself if a small sharpness edge is important.
As several have mentioned, when you work really close you lose so much DoF that it is irrelevant whether you use a 60 or a 105.
I don't know why macros tend to have CA, but both the D and G have some. Easily cured in an editor, however.
For hand held close-ups outdoors, I like a 60mm length. Indoors where you need artificial illumination a 90 or 105mm focal length is probably more useable.
Anyway either the D or G will serve you well. Take under consideration purchase price, repairability and resale value to make a decision.
Don't forget to consider the Sigma or Tamron line when looking for a macro. There is a Tamron 90 which is quite nifty, but I do not remember which 90 it is at the moment.