The 105mm Nikkor is a great lens, and well worth the money if your serious about your photographs, good quality glass and not so big as to be difficult to handle. If you get one of the micros , you can still work with extention rings in the future if you would like to increase magnafication factors, which seems to be the best of both world, macro capibility in the prime and still have the ability to go with the tubes if more magnification is required.

On another note, I have used reverse rings on both my 35mm and my MF gear for years and have never had a problem with lens element damage.