A box programmer needs to suit the needs of the majority. They have to make the programmer work at high elevation, sea level, in cold weather, in hot weather, bone stock, and with a bunch of mods as well as driving style. The end result is that to be everything to everyone there needs to be some compromise, but on an average truck in average conditions with average mods they work just fine. Move away from average, and the compromises start to build up.
The advantage of EFILive is that it is not a tune, it is software, so you as the end user can tailor a tune to meet your needs - your elevation, your mods, your driving style. You don't need to compromise because the tune is specifically for your application. If you add mods at a later point, modify your tune to best support those mods.
There are 2 methods of tune delivery - FlashScan V2, which allows you the end user to write tunes and datalog, or purchase tunes from a range of Professional Tuners, or AutoCal which is more equivalent to a programmer, but the Tuner writes custom tunes for your application, and the device is locked to that tuner.
Both units allow for data logging, so if your truck doesn't run quite right, you don't need to articulate what is going on, or worse....guess - let the data do that for you.
Both devices allow for concurrent multi-vehicle programming - FlashScan V2 up to 221 vehicles, and AutoCal 8, so your investment is not just limited to your truck today.
Cheers
Cindy