However, it is not correct to say that charcoal burns at a consistent temperature. It burns over a wide range of temperatures as evidenced by its color, from red to orange to straw to white as you give it more oxygen allowing it to burn hotter and hotter. Getting a roaring fire going will produce a much higher temperature at the grate level.

I also don't think that heating up the ceramic is the issue here. I ran a large Egg at 400 degrees dome temperature for 2.5 hours and the temperature of the ceramic by the gasket was only 180 degrees. Heating the Egg up to 750 degrees for the 10 minutes or so that it takes to sear a steak isn't going heat the ceramic up very much at all.

I think the issue is more with the burping of the Egg. This allows hot air to rush out over the surface of the gaskets and I think does far more damage than any heat from the ceramic. And if you have any sort of flashback when you burp the egg, this will indeed damage the gaskets. The carbon monoxide flame will easily exceed 1100 degrees. Rather than just burping the cooker, I would open top and bottom vents wide open for several seconds before doing any burping to minimize the rush of hot air out of the cooker and prevent any flashback.