Not out dated advice at all it's the Truth the T- Mobile network has more holes in it than swiss cheese . You have to wonder why no storm chasers use T-Mobile to stream live video or to get radar data . If it works for you and you don't travel very little then go for it but I could never live with GPRS and EDGE data speeds
I travel a lot inside and outside the US. No problems. Just keeps getting better.
PS - no carrier is going to help you when the tornado knocks out all the towers in an area. Which is why they use sat phones.