[LG V30 Questions & Answers] ChazzMatt:
Yes, as @schwinn8 noted, the S20 loses headphone jack vs S10/S10+, and I don't need 5G when LTE is still plenty fast. I already watch videos, I read news articles on my V30 with LTE. Phone calls and texting do not work any "faster" on 5G. However, 5G will drain your battery faster. :cautious: I'm not against 5G, but headphone jack is more important to me and lesser price. S10+ has bigger battery (4,100-mAh battery compared to the Galaxy S10 3,400-mAh), so for me it's better than the S10.

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The difference between the "factory unlocked" S10+ SM-G975U1 (analogous to the US998 Open Market V30) and the "carrier unlocked" S10+ SM-G975U (analogous to an AT&T H931 which has been given an unlock code) is the "U1" version does not and never had carrier firmware. For the "U" version, each U.S. carrier had their own firmware.

Now, if a "U" version is dealer/seller "carrier unlocked" it CAN be used on other carriers (much like a "carrier unlocked" V30 AT&T H931), but still certain frequencies may be missing -- depending on which carrier firmware is installed. To my understanding, on the S10+ "U" versions you CAN swap carrier firmware via Odin to turn an AT&T version into a Verizon version (like Frankenstein), and if it's already dealer unlocked, everything is gravy. However, if you REALLY want to make sure, just buy the carrier unlocked version in the first place with the carrier firmware you need. If you need Verizon, buy the dealer/seller carrier unlocked Verizon version.

To my understanding, these Snapdragon U.S. carrier firmware "U" versions can also be bootloader unlocked and rooted with Magisk just like the Snapdragon U.S. factory unlocked "UI" version.

Now, normally, I would be pushing the "UI" version which contains no carrier bloatware whatsoever. After all I own three B&H Photo US998 V30/V30+! So, why am I not doing that? Because in my case, I am an AT&T customer and

AT&T has a document

showing what services AT&T will different carrier unlocked phones, once HSPA is cut off in February 2021, specifically for "unlocked devices".

Below are the relevant Samsung Galaxy S10+ sections. "UI" factory unlocked version vs the AT&T carrier firmware S10+ "U" (but which has been carrier unlocked).

Hmmm....

This is only AT&T, this is not what Verizon will do, not what T-Mobile will do. Everyone's situation is different. But for me, it looks like the AT&T carrier firmware "U" version would be better, because not only does it have VoLTE (which AT&T calls "HD Voice") but also VoWifi (Wi-Fi calling). And if both the "U" and "UI" versions can be bootloader unlocked/rooted, then I'll get the one which gives me more capabilities. With root, I can always remove any carrier bloatware I don't want.

I'm sticking with AT&T for now because...

1) there's AT&T fiber running down my street and I may dump Comcast internet/TV and go with them, and bundling my phone would be cheaper package price.

2) Also, due to geography where my house is located, I have AT&T microcell at my house and if I switched from AT&T I'm not guaranteed Verizon or T-Mobile signal (or any MVNO) will be stronger. I'm not going to switch carriers just to find out suddenly I can't get a signal. My wife is on AT&T Prepaid (ridiculously cheap plan) and I'm on AT&T Postpaid (to qualify for the AT&T microcell). Starting the change process to another carrier for both of us would take time and effort, with no guaranteed results better than what we have right now.

I have a few apps which require root and I enjoy having full control over my phone. If I get this S10+, then I would want to bootloader unlock and root it prior to setting it all up and making it my daily phone.

I do see this caveat on the

bootloader unlock page

schwinn8 helpfully found:

Buying used from a dealer, I don't know how you would have any control over that. And I'm not going to buy a 2019 S10+ "new" in box (extremely expensive), which may not indeed be actually new but just refurbished with mix and match parts (lots of V30 wholesale dealers pull that trick). I would buy in great used condition from one of the dealers listed above.