Forgive me for starting this new post but, I after having this question assessed partially in different posts that I was ”hitchhiking”, I wanted make a quick summary and ask for a more direct advice. I am considering the DX to FX move from D90 to D600. My quick summary of what I read in the other related posts: - FX will be a big improvement over DX for DOF, wide angle shooting, and noise at high iso - Using DX lenses on the FX body is possible in crop mode, will probably yield a at par or better IQ at 10,5MP compared to my D90 12MP, but is not an interesting proposition So this is my doubt: The specific need that makes me think about upgrading is taking pictures of my children’s school presentations indoors at night (dance, theater plays, etc) when light is low and I am sitting somewhere in the back of the auditorium. I am currently using my D90 in ISO 1600 and a 70-300mm VC 4.0-5.6. What is likely to get me more improvement at the long end: 1) using a D600 in ISO 3200 with my 70-300 4.0-5.6 VC or, 2) using a D7000 in ISO800 with a 70-200 2.8 I guess the cost of a D600 is more or less the same of D7000 + a Sigma/Tamron 70-200 2.8, so, is more a results than cost driven decision. The other big use I have is taking pictures of my children around the house, but for that I feel that my Tamron 28-75 2.8 paired with my D90 is doing fine. Any advice will be hugely welcome.