bgmg, thank you for all of this compiled information.
I broke my last phone (it followed me into the pool) and am now using another Galaxy S4. I didn't realize it when I bought it, but it is the SPH-L720T, with the Sprint Spark, and I do get Spark service in some areas near my home, so I'm interested in keeping that service. I've spent the last couple hours googling, and couldn't find complete clarity on this, so I figured this was the place to ask.
I've already rooted the phone using CF-AutoRoot. If I flash on a stable cyanogenmod build (last stable jfltespr is CM12.1 from 2016-11-16), will I maintain Sprint Spark/LTE connectivity? If so, is there a benefit to updating my baseband version (currently NG5) beforehand?
As I said, I've done a lot of reading and haven't found anything definitive one way or the other. There are a LOT of older posts out there with conflicting information for the 720T. Some of them say flashing does work, but you will lose Spark, some of them don't care if they lose Spark because they're not in a coverage area anyways, some say that it will work but you just won't have the icon, and a hell of a lot of them just don't mention it one way or the other. I'm just looking for some sort of clarification here that I can upgrade to CM or SlimKat (only two I've used before) or something else without losing my Spark connectivity, if anyone could confirm.