I've watched the thread with interest as I'm facing a similar dilemma.
My main topic is orchid photography, as well as the odd wildlife, family, or other shot. However, orchids are my focus. To that end, my D7000 generally only wears the Nikon 105mm F2.8 MicroNikkor. However, the DX 18-55mm is also very useful, and I can see the Nikkor 24-85mm as a quick purchase when I move to FX.
Thoughts about the D610 or D800 given my interest and older lens selection?
Thanks
Honestly for your intended purpose, the D7000 gives almost equally satisfying results as my D800E as far as macro is concerned. Not enough reason for me to tell you to go full frame which I normally do suggest to go that route.
Are there any other reasons why you might still benefit from a FX?