I got the E74 right after upgrading to NXE - this was before they included this in the extended warranty, but they covered me because it would alternate with RROD - so they warrantied mine. Depending on your machine's age, if warrantied, it will be a free repair.
Nope.. sounds about right. They don't actually 'repair' your individual system. They just seem to swap the guts or the unit. Your Serial number is the same, but I never bothered to 'mark' my system to see what they replaced or not.
I must be one of the only people in the world who has purchased a 360 and had absolutely no problems with it. I read these posts and I'm like "boy I am sure lucky!" I'm sure its going to break one day, but almost 4 years in and the thing is still going strong. Crazy how this stuff works.