If you cannot see the increased acuity from a 24MP camera in 98% of your prints, you might want to work on your print sharpening routines. Or buy a better printer. Or print on smooth paper, not on matte paper, which mushes everything down to, well, mush. Or get some modern, high-resolving lenses designed in the digital camera era.
The dynamic range advantage the brand-new D610 has, according to DxO Mark testing, is 2.2 stops MORE DR for the eight years newer sensor in the D610, at base ISO.
A good comparison of the D600's 24MP performance, as it stacks up against the D700, and the D800e, can be found here, in Ming Thein's review of the D600.
The Nikon D600 review: full frame for the masses? ? Ming Thein | Photographer
I currently shoot 24MP full-frame Nikon. With good lenses, its results are far superior to the 12.8 MP FF Canon 5D and the 12.2 Nikon D2x cameras, at EVERY single ISO value. I can see it on-screen, I can see it in prints, I can see it in web-reductions. Higher acuity, better detail, better dynamic range, just better at every ISO value.
One thing Ming Thein has is
GOOD LENSES. VERY good lenses.
If one cannot SEE the differences between a brand-new 24-MP camera and one made when President Bush was still in office, it might be because one is
using outdated lenses, like the 300/4.5 ED~IF, for example, or other old lenses. I mention this because multiple times on TPF I have seen you claim that the Reagan-era [early- to mid-1980's] Nikkor 300mm f/4.5 ED~IF is the equal of newer 300mm lenses...so...perhaps your conclusions are based on older lenses and what you happen to own?
For example, if a guy is still using an 85mm f/1.8 AF or AF-D, he'll think a 12MP camera and a 24MP camera are basically identical, because, frankly, the 85/1.8 AF-D blows.