It's not so much the convenience as the problems other carriers bring. T-Mobile has no security, and lousy coverage, and is technically incompetent, but they're fairly honest and customer-friendly.

I could tell a horror story from Verizon about a multi-thousand-dollar roaming bill from someone I knew, from Google about being completely locked out of a phone number forever from another person, and lots of others.

Pick your liability.

On the whole, I found the risk of data theft from T-Mobile to be the lesser of the evils.