Those reading this thread should take a look at Gerard Pas's recent post in the Wildlife forum. He is using the D800 for birding and he seems to be thrilled with it, to say the least. His only problem is that he is now shooting passerines with a 300/2.8 and now has an imperative to upgrade to a 500 or 600, which you, Jim, already have .
Edit: Eric Bowles has a similar thread in the D800 forum here. There may be others already. I've been working on 3 hours sleep each night trying in vain to take advantage of the remaining spring migration season, so I'm not fully current on all the latest posts.
I predict we will see many more of these threads in the Wildlife Forum.
Two days ago I tried to shoot the Red Knots that were supposed to show up at Slaughter Beach, Delaware after the May full moon Horshoe Crab spawn. They did not show up. Yet.
Only the truly devout wildlife shooters show up at Slaughter Beach at 6am to shoot the Red Knots. It's about 3+ hours from any place that anyone lives, except the 50 residents of Slaughter Beach, which probably mail order groceries from Amazon. Mainly because it is about the most remote place left in the mid-Atlantic coastal area, It is about 10 miles to the nearest 7-11 (or public restroom with real plumbing) and in my book that is as remote as it gets for this area of the country
Anyway, I ran into a group of 3 photographers (all friends) that were all sporting brand new D800's with various long lenses. All were equally ecstatic about the D800 for wildlife. No one complained about the viewfinder. They generally felt that giving up 2 fps was a good trade for the other benefits of the D800. Since we had no Red Knots to shoot we unfortunately had some (too much!) time for gear talk.
I don't think the D800 is the perfect wildlife camera, mainly because Nikon elected not to let it shoot 8 fps in DX mode. But I think it well illustrates the paradigm shift that I think will occur once DX wildlife shooters think this whole thing through. It sure is making me think hard about how important those 2 fps really are to me, verses the other issues I have shooting wildlife on the D300.