I have an N900 and I am on T-Mobile in the States. I enjoy great service, 3G speeds and unlimited international texts for $5. Right now I'm in England and have swapped out my Tmo sim card for my Virgin UK sim card (so that I get cheap calls+free texts+free web rather than pay expensive roaming costs). When I go back to the US next week, I'll simply swap my Tmo sim back in. Hey friggin presto. Quick, easy, convenient and cost-effective. Now change the Tmo part to AT&T and I'd lose all that good stuff like unlimited international texts, lower bills and great service, and my data speed drops to 2G. Magically change the whole thing from GSM to CDMA and I don't take it to England. Personally, I'd like the whole merger to fail so I can carry on doing what I'm doing. But I know the world don't spin the way I want it to...