There's a review of the new version here
. 4 strats show that this is a very good lens.
And the review says: "The new DG (Digital) variant features an improved lens coating optimized for digital sensors." That implies that only the coating was changed. If that is the case the older lens should have equal sharpness be would be more susceptible to flare and ghosting in contra-light situations. But those can be avoided if you're carefully setting up macro shots.
Be aware though that I'm only speculating here...
The only thing that would hold me back is the short focal length for a macro. Normally 90mm/1o5mm or even 150mm are preferred over the short focal length macros of 50/60mm.
Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews
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