Six,
No you explained that rather well! My cousin has the Note 3 so I know what u said about the last part (on VoLTE) is def true. I wish HTC would hurry the F up and give us M8 ppl VoLTE. Would be nice. And make it available everywhere, not just major cities (it's avail in Chicago, but I live 25-30 min away).
I have a buddy who works for U.S. Cellular corporate, and he said the same thing. Unlocked phones, esp ones sold by one carrier but used on another's network, don't work AS well as when the phone is made for your carrier's network. International phones at least I believe work fine if released OFFICIALLY in the U.S. (i.e., Sony's Xperia Z2, which is ONLY avail that way in the U.S.), because they've been tested on ALL carrier networks/bands, but that's diff than using say a Sprint phone on T-Mobile's network, I believe. (Or using a phone that wasn't approved for all the major U.S. carriers.)
So far you're the only who seems pro-carrier firmware/OTAs, but that's ok. That's why I started this thread, so I can get all sides of the story. But if you read the previous posts, the other posters make a compelling argument that's pro-noncarrier. It sounds like in my situation I'm fine, b/c I'm pretty sure the int't M8 was tested on T-Mo's bands already. The firmware would just go along with that same data, so I don't think I'm having any loss of quality. Now if I carrier-unlocked my phone and tried it on Sprint or Verizon, or even AT&T......... then I would expect a loss of quality at some level.
Thanks,
RockStar2005