Hmmm... I seem to have left out comments about trans-Atlantic 550 use. With a bit of care in selecting map sets, having the North American and the "places most tourists go" European maps is not a problem. The transition from using the 550 to get to the US airport to using the 550 to head to the first stop after leaving a Euro-land airport is simple. Use settings to select the map set, change units (trying to use miles and feet in a metric world is discouraged - the road signs don't use miles, at all), and accept the pronunciation of local names will probably be horribly wrong. The rest of the business of operating the 550 is done automagically. If traffic reporting worked with your phone/550 combo in the US, they probably work in Euro-land, too.
If you were wise and signed on to an international phone/data plan, from your US phone carrier. Failure to do so and operate on roaming will probably suck several wallets dry. "Know before you go."
Armed with your 550, a portable car mount, place for the USB charger, and a phone, you and the 550 will be good to go on either side of the ocean.
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About TT support and the MyDrive app... For some reason, MyDrive stopped winning records for battery consumption, although it's still near the top on battery consumers. Force app stop doesn't work any better than before. The only way to take MyDrive off of the active apps is to uninstall it (most folks' option) or "freeze" it for rooted phones.
I called TT Support ask about the "app that won't die" problem, in hopes of finding there is an on/off switch or other "battery light" option. There is no on/off, no sleep mode. Pushing the matter a bit, the stance was "you must call your phone maker - they will know what to do". Or... "It ain't us, go bother someone else". How Garmin.