Ok heres my setup and concerns.
I currently love my D700 and use it as my primary camera with a 24-70mm 2.8 lens. I have a 300s for my secondary camera coupled with a 70-200mm 2.8 or 50mm 1.8 fx model, making it more like a 75mm. I really dont like to use the 300s with the 70-200 very often. I probably use my D700 setup 80% of the time. So thats another reason I want to upgrade. II also have a D7000 and just never use it.
So my thought is to sell the D7000, D300s and 70-200mm lens. With the money either buy a D800 and have some left over or spend a little extra on the D4.
My major concern is Low Light Capability, Dynamic Range, and Good focusing. As any Wedding Photographer knows priests dont like flashes in churches and Receptions can be dimly lit. Not to mention I hate using flash. I like natural light, so the best low light performer is what im looking for, after all thats why i went with the D700 in the first place.
My thoughts. I like that the D800 has a better dynamic range. I do not like that it is 36mp. I do NOT want all of that file space eaten up. I like that the D4 has a better high ISO capability and is only 16 mp, has double the life expectancy, and image is better, but dont like the cost of course. Not really sure why I would go with the D3s over these two, but that has been recommended to me.
So with that said. I am looking to have my D700 as my second camera (not backup) I will probably attach my 50mm 1.8 lens for my more artistic shots and low light help. And then use the new model as my primary with my 24-70mm 2.8. I may switch the lenses at the time of the ceremony if its dark and reception to get the most out of a low light situation. I love taking pictures with no flash so my fastest lens with a camera that can handle higher ISO would be best for that. And I already have a great system when I need a flash on my D700.
What do you guys think?
You can see my work at Lake Tahoe Wedding Photography