For those who are worried about data drops and refurbs, I think I can at least explain in laymen's terms why this occurs. Now, I'm not the most technical guy you're going to come across, especially here on this site. But it was explained before.
Back on our OG Droids, there was so much ROM development, it was insane. We'll probably never see the plethora of availability we had in those days. One of the things that always confused those of us who our enjoying the fruits of others labors (which reminds me, always donate to your fav devs!) was that some ROMs worked great for some, and terrible for others. It depended on build, kernel, theme, whatever. But why did it work for you and not me?
When they mass produce these chipsets, they're stamping them out of much larger circuit boards, circuits going this way, that way, and what not. This causes no two phones to be exactly the same. And certain software hiccups when talking to hardware.
Ok, so you bought a phone, but it's hiccuping. So you send it back and they send you a new one. How many people did that exact same thing? Probably a lot. More than half the phones that go back to the manufacturer, I'm willing to bet. So when they send you back a refurb, the likelihood that it was sent back for the same exact reason you sent yours in is pretty hide. Thing is, it has the exact same software as the one you sent in. As long as that same software is on there, it'll never work right.
That's why I'd recommend rooting your phone, and flash diff software. It can make a world of diff. And I hope this helps your understanding, it certainly did me when I was told by people who could explain it better than I ever could.
