Yes, I did replace it this past spring prior to selling my oldest 1DX body when it had reached my normal 3-year lifecycle (purchased from the first batch in late spring 2012).
Note that I sent it in for annual maintenance and never had a failure although I was beyond 350K actuations. The reason for sending it in this past spring was for a complete overhaul just to do right by the future purchaser of the camera. At my request (and insistence) they replaced the mirror box, shutter assembly and a couple other minor items. It was under $500 total with the Platinum CPS discount.
Note that the shutter count was not reset. It didn't affect the sale price, because I had all paperwork to show to the buyer that the restorative work was truly performed, including my letter asking Canon to perform all work needed to restore the camera to brand new equivalent condition. I feel confident that the camera will work flawlessly for another 400K photos at least.
It is very common for me to exceed the maximum actuation count on my Canon bodies, and with them I have never had a shutter failure. In my experience over 1.8 million digital photos, my only shutter failure is on a Nikon body. Even in that case it was understandable--it was a D7000 that I used as a backup when shooting outdoors in extremely hot weather to keep more expensive bodies from overheating. It failed after 136,000 shots and could not be repaired. Nikon replaced it for free within warranty.