Nikon are to announce the D610 on Tuesday. I've used a D300 for the last 3 years and really like it. But I need something with much better low light performance as I now do much of my diving in to wrecks in 60-80m range in Irish waters. Was considering the D600, it seems to be fantastic at low light and is very reasonably priced, the only thing that puts me off is the really AF system. I've considered the D800, but it is considerably more expense, and I definitely dont need 36MP.
Rumours so far is that there will only be a slight increase in fps, from 5.5 to 6. Increase the area the AF covers and I would buy one in a shot.
Anyone out there using the D600 and how you finding it?