Is this setup crazy?
It doesn't make much of a sense to me. I would replace the D600 and the 24-70 combo with a Panasonic 12-35mm f2.8 and you already have exactly the same reach and speed in a much more portable package with very little sacrifice if at all, and saved a big amount of money.
The money you save can be spent on some nice primes and maybe a second MFT body if you need and makes your package even more versatile.
Of course, it is nice to have a FF body if budget is not an issue, the question is do you really need it?