Galaxy s4 GTI9500 android version to update
I have an S4 on Verizon. I haven't had any issues since the update to Lollipop or before that with Kit-Kat. However the Lollipop update took up a lot of space on my phone which was a pain.
If I were you I'd go straight to Lollipop which, if I understand correctly what FOTA means, is FOTA capable. You shouldn't have any issues from the 4.3 'catastrophe' as you put it. I will warn you though, lollipop changes the look of a lot of things that do take some getting used to. But I've had it for over a month now and I like it same or better than before. I get much better battery life with Battery Save Mode, just don't use it all the time or it becomes ineffective.