Yes,ive heard of that! Nowdays finding a brand spanking new Xenon Motherboard its like finding water in the desert, they are rare and scarce, but nobody would buy a Xenon X360 unless you are a serious collector or perhaps modder,but even modders go to the newest revisions like Jasper or Falcon, not to mention Corona and Trinity can be RGH´d, i know Corona can,but Trinity (what are the odds).
RROD like you mentioned isnt always releated to overheating,ive seen X360s RRODs by other issues,and its described in the Owners Manual, but unlike the PS3, various RROD combinations can help to detect the source of the problem, which its a good thing,but from my perspective,not to bash the X360,but in terms of quality and reliability, i think Sony´s machine wins by a long stretch, but the 7th Gen was always known with reliability issues.