As others have said, AF is slow...certainly in comparison to those lenses mentioned. It's usually the subject of many a 'Nikon rumour' regarding an AF-S replacement over the last couple of years, so probably not worth holding your breath (oh Nikon, please prove me wrong!). IQ is best around the f/8 mark, so be aware there some 'bad IQ' reports can be technique and settings related. Lots of other options on the market, but you would be probably wise to have a look at Sigma's superzoom stable....have just sold on my Sigma 120-300mm f/2.8 (secondhand prices are around those of a brand new Nikon 80-400mm) whilst there are a few on here who shoot class photos with Siggy's 50-500mm...on a D3 it just might be worth trying and ignore any lens snobs!!