Currently have a family of four on an AT&T family plan and am interested in taking advantage of T-Mobile's 10GB for $140 plan. However; my wife and I just upgraded to the 6s. Would it make more sense to return the 6s' to AT&T and then move to T-Mobile or should we just rely on T-Mobile to pay the early termination fee and the cost associated with the new devices. Prior to upgrading, we were both out of contract on AT&T (in other words, we owned our old iPhones). Returning the devices will be the 'cleanest' way, but will create more work for us. Going the rebate route will require more up front expense, but would be less time consuming. Anyone have any experience with either returning devices to AT&T or having T-Mobile cover costs? We will ultimately save over $100 per month and get vastly more data per line. I understand T-Mobile coverage is not as good in some areas, but I checked the coverage map and I am satisfied.