That is what I do now but entails two phones (since I have to be available on my US number). Before the Euro Tariff it would require a local SIM for each country but now I just have a Dutch Vodafone SIM I keep alive (can top-up with US credit card) which is good in EU + Switzerland. Plan was to transfer my T-Mobile postpaid to the eSIM but TMO has been dragging their feet so this (Ubigi/GigSky) seems like an alternative.