Do you plan to keep the 5d3 for wedding work too? Or did you plan on replacing the 5d3 with the 1Dx? If so, and if you're using/liking the silent shutter on the 5d3, you're going to miss that sorely on the 1Dx. The silent shutter mode on the 1Dx is not very quiet.
No no the 5D III is a definite keeper, I will sell the 7D.