I just got back earlier today from Costco that offered a promotion, and then a Verizon Corporate store.
First Costco, when I first went there, they promised that they'd give me the ETF reimbursement and trade in value of my iPhone, plus a Costco gift card. As we were getting to close the deal, the sale rep backed out and said they'd only do the gift card (no ETF reimbursement or trade-in offset to lower the cost of a new phone). That basically killed the deal for me.
We then went to a Verizon corporate store, and they explained the promotion similarly to what the fine print reads. They'll pay my ETF less the trade-in. In the simplest example the salesman used, I owe 300 on my ETF, and I get a 100 for the trade in. So I'd have 100 dollars to apply to a new phone, but only 200 towards the ETF. In my actual situation, VZW will give me 275 for the iPhone 6 plus but my ETF is 175. Since my ETF is lower then the trade-in, its really an either or situation, I can choose to have VZW pay off my ETF, or I can use the trade-in be applied to the cost of a new phone. That basically killed the deal for me (again).
At this point, it doesn't make financial sense for me to switch. I think what I'll do is let my contract run out, and if the time comes we decide to leave ATT, then we'll do it with better terms from VZW