Upload & Sell: Off
I guess I had a pretty good copy of a Nikon 35-70 f2.8 D, I mean, I don't have a D800, but I was never let down. I'm with Sonofjesse2010 in this one, if you like your pictures, keep them. The law of diminishing returns is strong on lenses, so I really doubt you'll see a world of difference, but that's just my humble opinion.
It's easy to get consumed by Gear Acquisition Syndrome, because you'll always chase some kind of magical lens properties that you'll never get, simply because they can't live up to your expectations. I've been there.