My own personal pet peeve doesn't even have anything to do with overheating....why on earth Canon equips cameras with two card slots then only lets you create backup recordings for photography and not video is completely beyond me.
You do realize that an SD Card is not capable of ingesting 8K RAW or 4K 120 footage, right? The solution would be dual CF Express cards. Then people would complain that you needed to drop so much money on storage. Perhaps on the 1DX mirrorless replacement, but this is not the camera for that.