The 85mm lens will give you about half again as much working distance between you and your subject, which can be quite a benefit. You have latched onto the biggest downside of the lens, though, and that's that it locks you into the DX (crop sensor) format. On the other hand, a 60mm macro lens on an FX (full-format) sensor will leave you with some very small working distances, since the magnification factor needs to be 1.5x as high to make the "same" picture on the larger sensor. The reduced working distance makes lighting your subject (or just getting out of the way of the light that's already there) a lot harder.

If you're not religiously fanatical about having the Nikkor name on all of your lenses -- if you're more interested in the images you can make than in creating a pristine collection -- then do yourself a serious favour and take a look at the Tamron SP 90mm f/2.8 DI Macro II. It's a wonderfully sharp, contrasty and distortion-free lens, it's full-frame (FX) -- and it's about the same price as (or less than) the 85mm Nikkor DX lens. I've owned it in several versions going back to the multi-mount Adaptall 2 version in the '80s, and it just keeps getting better and better over the years with improved coatings and so on while the original (excellent) optical design has remained intact.

If you do want to keep to the Nikon in-house lenses, then I'd probably go for the 85mm and look at trading it in on a 105mm when you go to full-frame -- you'll likely find the 60mm less useful than you think on a full-frame sensor. That extra working room really counts for a lot.