>Google shuts off the data on Fi after you've been outside the USA for a month. No problem, I'm happy to pay $25 a month for a 'dataless' connection that gives me SMS and voice.

To be somewhat more specific: while I travel extensively and am in the US often, I am often outside of it for more than a month at a time, and it appears that Google will shut off data outside the US if you use data outside the US for too long. If you are using a different SIM for the primary data connection, it appears that they won't even if you have it enabled as a backup.