I travel o/s almost every month, and usually to Nth America but always register. NOWHERE is exempt from natural disasters of some type or another.
What's the downside? When you leave you fill out the Departure Card so "the gov'mint" knows that you are at large. If "something" happens, and those at home are concerned for your safety, at least there will be something for F/A to work on.
People who don't register I think are the same type as those who ostentatiously igbnore the safety demos on aircraft. 'I'm too cool /I'm such an experienced flyer to show I'm worried about my safety". In my mind, they are the last for me to help when sh*t happens.
Register just before you go and also don't forget to tell your cc supplier that you might be using it o/s (else it may be bounced).