I'm in the same boat. Unless things improve magically this weekend or Samsung release a patch I will be calling for a return on Monday. As you say the Mi 10 Ultra isn't really available and the one plus 8 Pro has no SD support which is important to me. Think I'm just going to use my Note 8 and hold off for a while. If only the Note 20 ultra had better battery life it would be near enough perfect but sadly not unfortunately.
So why are some getting good battery life and others getting very little?
You would think all the phones were the same but there's definitely something going on here.......
I wish Samsung released SD version of Note20 Ultra in the UK. Such a shame US gets better phone in terms of speed, battery life and even usage of thermal components.
Is US version would be OK to use in the UK?
You would have no warranty support for the imported phone.
5G may not work and I've read some are experiencing intermittent signal loss which maybe due to the frequencies and bands.
It's suggested to buy a Hong Kong version and not one from the states.
Also check that there is no Region lock.
And check any import fee's too.
Current Phone ~
Samsung Note 20 Ultra 5G SM-9820 _256Gb SnapDragon 865+
Samsung One Ui 2.5/ Android 10.