Wed 19-Dec-12 06:52 AM | edited Fri 21-Dec-12 04:40 AM by jrp
DX lenses are generally less expensive than FX lenses of the same generation because they are smaller, have smaller sized elements of expensive glass. G lenses do not have aperture rings in neither of both DX and FX incarnations.
In general, full frame lenses that do work well on FX will also do well in DX. In fact, usually even better because chances for vignetting are none since on DX you will be using just the lens' center, area where there are no light fall-offs.
You need to compare each DX lens by lens against its FX counterpart in the same focal length.
Talking about your example, all the 80-200mm lenses do perform very well. All are FX lenses. Comparing them to the 70-200mm versions, (also FX lenses) the latter may show better image quality, simply because they have newer features incorporated, like nano coating, being from newer generations.
I wrote "may" because it largely depends on how large you print.
Also, you need to define what is "better" for you. Pro FX lenses are fast (wide aperture) while most DX lenses are not, to make them more economical, especially when it comes to zooms.
For example: The 12-24mm f/4G DX AF-S is not better than the 14-24mm f/2.8G AF-S. None has an aperture ring, but the second one (FX) is faster and has improved image quality because it is a newer generation lens. The DX is cheaper; again, because it is smaller.