My original 360 already had a red ring of death but it was still in warranty. Of course Microsoft won't do the fix that the repair kit that ifixit sell but it worked. Last week my 360 got a E74 issue so I decided to buy the Red Ring of death fix and reflow the mother board while I was in it.
It went smoothly. I do with that some of the guides had a bit more info. And I also wish there was a mobile version of the website to see it more clearly. Overall though it was easy. Just took a while. And ifixit was great!
Get a good heat gun. Make sure you have a good 3 hours.