Quick question for people using live view focus on D800 and/or D600

Yes. 24MP on a much larger area. The D600 corresponds to a 10MP DX, not a 12MP. No big deal, I don't think the differences are really visible, but never the less, the resolution is lower. Anyway, the Op has mentioned that resolution is very important for him, and in that case the order of cameras currently is: D800E, D800 and then the D600. The differences between the D800E and the D800 are just marginal, but between the D800 and the D600 is noticeable.