Not sure why you would get "shut down" mid way through your trip unless you are doing crazy things like adding a ton of AUs or other odd things (And not sure why you would do that while traveling on random wireless networks). Let them know you are traveling and you are fine. "Random" FRs are sprung by oddities. Traveling around and purchasing things like food, hotels, etc are not one of them.
My "random" FR came from adding 15 AUs in one night prep'ing for SBS.
I don't mean FR, I mean amex PRE-PAID randomly deciding to suspend your account (as they did mine). My account was suspended without warning and I still haven't gotten it back open again. I made no transactions, this was solely because I logged in from an overseas computer.
My point is just that this may be a great additional card to take when traveling but I wouldn't rely on it. For starters they don't even have 24/7 customer service (Major inconvenience when I've been trying to get ahold of them for over a week and am overseas - my card still doesn't work).