DxO Marks_ D7000 __ D800
70-300 ___12/13 ____ 20
28-300 ____10 ______ 17
They have not yet published the results for a D7100 but I assume it will be closer to the D800 than the D7000.
I have a 28-300mm which I got for my D200 but knowing I would move up to a FX format camera which I now just have. For general use when travelling it is hard to beat. You do not have to constantly swap lenses. The very slight drop in performance is more than compensated for by its versatility. You can be taking a landscape shot one moment and then zoom and track a bird that is flying past the next. If I was setting out specifically to photograph birds I would opt for a narrower range telephoto zoom but for recording a place I am visiting it is the answer for me.
I will come back to this reply and post a couple of images taken with it. I am now back.
Note: The first three are limited by the performance of the D200 not the lens and were all taken the at the same place one weekend.
D200 @300mm
D200 @28mm

D200
D800 @300mm using close focussing.
