I know there's a huge concernes over ATTWS phones and Cingular network... will sim cards work in both... etc. I don't think there should be much worry.

Well, as a customer who was with a company that underwent mergers and buyouts, I never had a chance to be concerned. I didn't hear anything about DeutcheTelekom's buyout of Voicestream... or Voicestreams previous buyout of Powertel. (Yeah, long time customer.) Anyway, the initial handset I had back when I first started w/ Powertel still works with the new sim cards/service with T-Mobile, two takeovers and a different state later. I really don't think there should be any worries re: handsets and the new company. 🙂