I did not see a thread on this so here are some things I discovered and also question. This is seat of the pants eyeball calculations. I very recently decided on a D600. Having moved up thru the D70, D200, D300 I have a few nice DX lenses. I plan to still carry the D300 like I did the D200 as a back up. I read about and realize the difference in image size. I know about the DX mode on the D600 that drops to about 10.3 megapixel. However I tried the DX lenses with out going to DX mode on the D600 to see what the results were. I can crop what I want myself. It shows 24.2 megapixel in the file. My 12-24 DX is usable as a 16-24 without vignetting or getting the "tunnel vision" My 17-55 DX (my favorite) becomes a 24-55 The 16-85 DX, dark corners at all focal lengths on the FX but turned out to be a very sharp lens on the DX cameras. Center crop possible. So not being too proud to TRY a 24-85 "kit" lens, especially for the kit price (could be a mis-nomenclature of past stigma associated with that name), I shot some with my 70-200 2.8 and compared to the same zoom level on each and can say at 50% pixel peeping, yea, there is a slight edge difference, but not much. Depends on what you are shooting for. Prints looked about the same. I don't shoot many resolution charts and don't mind some technical reviews about what they call problems with just about every lens out there. The proof is in the image and what you are going to do with it. Looks like this may open me up to an 85 for a prime. So I do have some close overlap but depending on the intended project there are some good options. The 17-55 has been a steller lens and what I use in the studio the most on the D300 but will probably shoot some 1000 plus images for my daughters dance studio with it this year on the D600. That's just two to three days of shooting!