I Would say....The 5D is more discrete on a wedding. Some People get scared of such a big camera like the 1Dx. And for the price of the 1D you can buy two 5D's. Two Cameras with two different lenses and you can act better on a wedding.....
Before: Canon-Fanboy with 16 Lenses
After: Nikon D4, Nikon D800, Nikon D610, 10,5mm f 2.8 DX, 14-24mm f 2.8, 16mm f 2.8, PC-E 24mm f 3.5, 24mm 1.4, 24-70mm f 2.8, 28-300mm f 3.5-5.6, 35mm f 1.4, PC-E 45mm f 2.8, 50mm f 1.4, 58mm f 1.4, 70-200mm f 2.8 VR II, 85mm f 1.4, 105mm f 2.8 VR, 2 x SB-910