I own the 1DX and the 85 f/1.2 II and I can say that I would probably stick with matching camera bodies and buy the 85 if you had to spend money on something. Having matching bodies is very important unless you have crazy skills and can effortlessly switch between bodies when shots have to be made instantly (weddings can move fast). The 85 is a great lens but I find that it can be a bit unpredictable on some bodies. The DOF can be very shallow at MFD when shot f/1.2 to f/5.6 and I find it a bit slow on focus and accuracy so I would not trust it for the money shots unless they are posed. When that lens does hit, it really hits and produces some of the best shots I have ever seen (par with the 200 f/2 and 135 f/2 of which I own both).
As a side note, I have not found a church yet that had f/8 light when the bride walked down the isle (at a reasonable ISO) unless you are using flash which most are not. It must be dark here in the Midwest.