I heard the DF was the best in low light due to having a D4 sensor. I love the small size too. I take astrophotography and in your opinion is the noise difference that dramatic in the D610. I can buy a D610 now or save up for a DF. On sheet the D610 is a no brainer but it doesn't seem that way. Yes you're paying a price for the looks but I feel it's much more than that. Plus you can use vintage Nikon Lenses.
I would defiantly go for the DF if the mega pixels were just a little higher. I crop my astrophotography a lot.
I shoot day photography also street photography, wildlife and landscape.
Thanks!
Read more: I'm torn between the D610 and Nikon DF?