Upgrade to 6D from 7D ?

I currently own a Canon 7D + 17-55/F2.8 + 70-200/F2.8 IS mark II. Great setup, but to be honest I don't use it all that often except for paid fotoshoots (about 5/year), which nets me about € 2.000/year which I always invest in new material.

Now, I also own a NEX6 and a couple lenses and find that I'm using this little gem a lot, simpy because it's so light and easy to take with me.

But I still need a SLR to make some money off my photo's, so I'm now thinking to maybe get a 6D +24-105 lens. This would make for a simpler setup than I have now with a (I suppose) better ISO ratio. I would consider going fullframe because when I use my SLR, I tend to shoot almost exclusively indoors or in dimly lit conditions. And I don't use flash, ever (just my style).

Would an 'upgrade' from what I currently have to a Canon 6D be worth it? Or should I look at other options? Or is the jump from APS-C to FF just not that big a deal?