TMo has had BYOD for quite a while. They put up with me and some of those unlocked EU phones I've had. Or used phones, and now the Nexi. Except for the "fees" that all carriers pull, TMo has left me alone. The locals know my phones are rooted and all TMo bloat is gone, so no extra $ that way. I've been able to refuse any data on the other 2 phones - 1, user isn't in States, and 2, Vulcan would have no idea. The 6085 did Tzones. Since I've never subsidized a phone, I like having the option of getting what I want.
If TMo is getting the iphone without restrictions on price or sales, then they are far smarter than Leap.
If you are into Samsung - rumor has it they are opening a store within a store in Best Buy.
Since I prefer GSM, I checked with ATT when the merger between TMO and ATT was on. No dice. No services I wanted - all bundled. I won't do Sprint or Verizon.