I don't think there's a functioning 5.0 ROM for the US S3s. But CM12 has started being worked on, so maybe I can hold out hope. If CM doesn't support the S3 anymore, someone on XDA can still make a port based off of CM, right?
I don't know how all this works. I'm back on rooted TW, like I said earlier, because data actually works in my house on TW. On CM or anything else, I learned something about "RIL Stacking" or something like that from XDA and apparently it sucks on AOSP and is best on stock ROMs, or something like that.
I used 5 GB of data this month, and it still wasn't with TW ROM the whole time, so a week or so of data was kind of lost. I have Twitter syncing about 6K tweets a day and downloading images beforehand. And I use Hangouts and Reddit is Fun on there, too, along with sports apps updates. So I guess it adds up. I just do it so I'm using even a gig of my monthly unlimited data. I feel like I need to make a switch to ATT so I can get coverage in my house, at least, and still get 30GB of family data which no one will ever use in my house.