Actually, you don't know if you're getting the same console back. It's more likely going to be a refurbished one (i.e., one which blew up earlier and they already fixed). You're supposed to hang on to anything other than the box itself, like the HDD and any of those fancy painted fronts.
The 3-year warranty only applies to the red ring of death. Even so, I'm surprised that there isn't a big class-action lawsuit over this. This is clearly a design defect, and people should be entitled to get replacements with that defect corrected, which would mean the latest systems with the design changes.