For one person, staying on the regular subsidy is probably = or < in cost. But, for a family that is currently paying $15 a month per phone on a family plan, it is more.
Looking at 2 year cost, just for the 2 phones we plan to switch right now:
If I buy 2 new phones outright, the cost is $1300 and then 2 years of service at $15 a month per line for $720. This gives us no commitment and the phone can be sold whenever. Total of $2020
If I use Next, the cost is $1300 (spread out over 18 payments) and then 2 years of service at $15 a month per line. This can be paid off any time after month 2 and then we own the phone, can sell it, and have no commitment. Total of $2020.
If I use the subsidy, the up front cost is about $460 ($199 per phone plus $30 upgrade fee), and then the per line cost goes up to $40 a month (2 years = $1920). This requires a two year commitment. At the end of two years, we can sell the phones. Total of $2380.
Because AT&T agents have given conflicting answers about whether upgrading 2 phones on the plan will result in losing the $25 discount on all the phones still in contract, the subsidy option could potentially be another $150 a month for us, because we have 8 phones on the plan.
I've been told 2x that we can upgrade using Next and not lose the $25 discount on the other 6 lines, but am going to ask again and try to get that in writing before we decide. If that's not the case, then we will buy outright. If it is the case, then we will probably do Next, primarily because we can preorder and I'm not able to stand in line.