Before I bought the 6D, I had the 5Dc and the 7D. I needed something with low light performance (ISO and AF) for events and the 6D performs well. I would say that 90% of my shots on my website are from the 6D. Go here for some sky shots: http://hmm-photography.format.com/nighttime#1 (all at ISO 1600). I have some pictures from a few events at 25,600 (http://hmm-photography.format.com/2195345-live-music#1).

I would personally go with the 6D too.