Can Apple's iPhone upgrade deal work for you?

Q. Is Apple's new iPhone Upgrade Program a better deal than the carriers' early-upgrade programs?

A. Yes, depending on how much any of these three conditions apply to you: You're afraid you'll break the phone, you travel internationally, or you'd rather not deal with selling a used phone yourself.

With Apple's new initiative, available only at its U.S. stores, you pay the list price of an iPhone 6S or iPhone 6S Plus (starting at $649 and $749, respectively) over two years of monthly, interest-free payments, plus the $129 cost of its AppleCare+ extended warranty. Starting a year in, you can trade in the phone for a new model.

AppleCare+ provides two years of warranty coverage, including repair or replacement for two accidental-damage incidents after a $99 fee each time. On older iPhones, the AppleCare+ rate and per-accident deductibles are $79 each.

Those costs beat what you'd pay under the wireless carriers' handset-insurance programs.

The new iPhones sold under this upgrade program come unlocked and stay that way even after activation on AT&T, Sprint, T-Mobile or Verizon. You can use them with any compatible wireless network in the world by popping in that service's Subscriber Identity Module (SIM) card.

Gallery: Apple product event

Internationally, you can save hundreds of dollars in roaming fees by buying prepaid SIMs from local carriers.

For example, a €20, 500 MB SIM provided all the data I needed when I covered the IFA electronics trade show in Berlin earlier this month. At AT&T, a phone with installment-plan payments left would remain locked, tying me to roaming plans that cost $120 for the same data.

T-Mobile provides free slow-speed 2G roaming that can suffice for personal use, but faster access on a phone with payments pending would require a data pass like its $50 500-MB add-on.

At Sprint and Verizon, things are better. At the former, I'd have to be 90 days into a plan to get the phone unlocked, but otherwise roaming is only $30 a gigabyte, billed per kilobyte. The latter sells all of its LTE phones unlocked.

A phone that's unlocked domestically, as the iPhone is under Apple's upgrade program, can also be used with cheaper prepaid services in the U.S. if you bail out of a no-contract plan like those standard at T-Mobile and Verizon and increasingly popular at AT&T and Sprint.

What about the early-upgrade math itself? Here's what you'd pay to keep a 16 GB iPhone 6s for a year until the arrival of an iPhone 7 makes it shameful to be seen with last year's phone:

• You'd pay $389 to Apple -- which, remember, includes an extended warranty while the others don't.

• At AT&T, the Next 12 payment plan would cost $390 over those 12 months.

• Sprint's iPhone Forever phone-lease plan would add up to $180 after a year if you trade in a smartphone first, $264 otherwise.

• T-Mobile's Jump! On Demand would total $240 for a year, but that will rise to $324 if you sign up after that promotional rate expires.

• Verizon has no early-upgrade deal, so you'd have to pay off the phone and sell it to somebody else yourself.

That last option can be the cheapest overall. As Jennifer Jolly explained here earlier this week, your options range from selling it yourself via eBay or Craigslist to unloading it to a reseller such as Gazelle or retailers like Amazon and Best Buy.

If you decide the iPhone 7 isn't all that and you wait a full two years to upgrade, just go with the carrier whose coverage and plans work for you. Which Apple's plan frees you to do -- at the cost of locking you into getting another iPhone. The carriers, in turn, lock you into their services but offer a broader choice of hardware. Whose embrace would you prefer over the next year?

Tip: Sprint's Open World plan may not work in your world

In most of the Americas, Sprint's Open World plan is better than even T-Mobile's terrific international roaming, since it provides 1 GB of free high-speed data. In many other countries, you pay just $30 a gigabyte.

But in others, choosing that plan limits your phone to WiFi service. And to avoid that (not that paying $40 for 40 MB of international roaming is any prize), you have to take Open World off your plan before you leave the States.

There's not much of a pattern to who's in and who's out — for instance, the Netherlands Antilles are part of Open World but the Netherlands are not — so check Sprint's list before you get to the airport.

Rob Pegoraro is a tech writer based out of Washington, D.C. To submit a tech question, e-mail Rob at rob@robpegoraro.com. Follow him on Twitter at twitter.com/robpegoraro.