lol, I never said anything about reliability or warranty... just said "Something to keep in mind". My 20gb fatty is still going strong too. ;) Can a new motherboard fail? yes. Is an older one the more likely of the two to fail? Probably
The thing with refurb's though is the parts inside. When they refurbish something, they only replace/fix what needs to be done. So while you might get a console that has a new hard drive, and new disk drive, it might have a year old motherboard already. Just something to keep in mind.