Nikon 200-500mm lens VS Tamron 150-600mm lens PRO & CONs ????

On the generation 1 of the Tamron you really needed the aperture up at f/8+. I spoke with the Tamron rep last week and he told me the wide open end of the lens on generation 2 had been greatly improved over generation 1.

Not had the 200-500 but have had both 150-600s, nothing wrong with the Tamron (now) but i felt the Sigma 150-600 had the edge for IQ, choosing now though the 200-500 would be difficult to ignore.

I have the G1 Tamron version and would have a problem splitting the G2 from the Nikon as the G2 has focus tuning throughout the zoom range with the use of the base, The Nikon I think will hold its value better .
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I have the Tamron "G1" and am facing the same choice. Having shot with the G1 quite a bit, the biggest thing I'm looking for is IQ wide open. I thought my shots with the Tamron were okay, but after reading a bunch of owners complaining about it being soft wide open and also hazy at 600mm, I've looked through most of the shots I've taken and can agree. Nikon is currently in the top spot on my list, mostly because the IQ is very good at f5.6, whereas the Tamron (both of them) requires stopping down to come close to what the Nikon delivers. Then again, the Nikon also doesn't have the extra 50mm on the short end & 100mm on the long end like the Tamron. Still looking and debating myself, but as I mentioned, the Nikon is the top runner for my needs. I almost didn't even consider the Nikon because a few people have said the AF is slow. But, a ton of birders are saying the AF is no slower than the G1, which has been perfectly fine for me. All I can say is good luck reaching a decision!

I can only speak for the Nikon with first hand experience.
The good.
Constant F/5.6 (Important if you're going to use a TC, although I don't recommend it for action shots.)
It is just as sharp wide open at 500 mm then it is stopped down.
The IQ is fantastic, bokeh is awesome .
For BIF shots the VR in "sports" mode is the best VR that I ever used. (I always use this lens hand held) I have taken shots at 500mm with 1/200th SS with no camera shake . sharp!

The not so good.
Zooming from 200-500 takes more then one turn of the wrist.
Not crazy about the lens hood.

Of these two lenses Nikon 200-500 & new model Tamron 150-600 G series which has the fastest auto focus especially BIF. Thanks

Bill