Have an ETF Calculator:
http://www.myrateplan.com/contract_termination_feesAnd an ROI Calculator:
http://www.techmeshugana.com/tools/wirelessroi.htmlI look at your spreadsheet and wonder where you're getting a lot of your numbers. Lots of WTF numbers, like the $1000 handset cost with Ting. Have a few pointers to chew on.
Refurbished Sprint iPhone 5's through Ting's Glyde storefront only run $250 a pop. Equivalent Sprint 4S units to what you have are $160.
Page Plus activates iPhone 4/4s units now, though you're dealing with Carlos Slim. Selectel is starting to look like it might go the distance, but I'm not sure if they can activate iPhones... and there's been an internal Verizon memo that might take the wind out of Selectel's sails regarding ESN activations and flashed phones. Your cheapest path without generating more electronic waste and keeping the investments you have already would be Page Plus. Setup through Kitty Wireless is recommended. Break-even with PP's $30 plan using your existing phones would be under six months, it would be
way less if you could actually get away with The 12, which I'm assuming is a possibility if you're
seriously entertaining Airvoice's $10/month plans, though I question that wisdom if you think Ting is going to cost you $65/month.
T-Mobile's "ETF payoff" gimmick is just that. It's a sucker's game to get you roped into a two year contract buying new phones.
The Republic math falls apart long term when you actually only use what you need in services, especially when you have to buy new equipment that you may not even like given your iPhone affinity.
Why do you think you can't take a smartphone to Airvoice? They're a GSM provider, any phone that activates will work. iPhones are a PITA due to Apple, AT&T, and iOS7, but that doesn't eliminate other smartphones that you're willing to consider. Even the new $130 carrier unlocked US GSM based Moto E should work with any AT&T or T-Mobile based MVNO.
Finally,
nobody needs that much data.
(edited after response)