Should I update to Big Sur?

It appears you have been doing your homework - Great and continue doing so :-))

Some the below, you will already Know but on the off chance something is overlooked.

Tips How to Upgrade to Big Sur 

There are several points to consider before attempting the upgrade to Big Sur. The most important is Due Diligence on the part of the User and is a Prerequisite for a smooth upgrade.  

The below points should all be consider Before attempting the upgrade.

Point # 1 - Are there pre-existing Unresolved Software Issues. They should be resolved prior to upgrading - they may carryover to Big Sur making the system unstable / unusable.

Point # 2 - Are there any AntiVirus, Disk Cleaner, Optimizers, Defrag, VPNs etc installed which should be removed as per Developers Instructions. They are useless, unneeded, cause havoc and interfere with the normal operation of the OS and may even Corrupt the OS requiring a Reinstallation. The Built-in Security of Big Sur is all that is required.

Point # 3 - What are the System Requirements ie: Empty Space Requirements specific to the Big Sur.

Point # 4 - Does the intended computer qualify for the upgrade.

Point # 5 - Are the installed Applications / Extensions compatible with Big Sur. Check with the Developer for compatible Apps / extension or do they offer updates. Same goes for Third Party Drivers for Printer, Scanners etc.

Point # 6 - If upgrading from Mojave and earlier versions of macOS - Remember that Big Sur does not support anything 32 bit. These include Applications, Extensions and Drivers for any devices. There is no workaround.

Point # 7 - Do I have a Rescue Plan In-Place. This comprises having 3 Backups using 2 methods and 1 Off Site incase of Theft, Loss or Natural Disasters. A Time Machine Backup  is very useful and can be used to Revert to Previous Working macOS. For addition purposes - two Tested Bootable Clones each to separate external drives. This is insurance incase the upgrades goes sideways. At least one Tested Clone and / or Time Machine Backup should be Off - Site

Point # 8  - To upgrade to Big Sur will require a quick, stable and reliable Internet Connection - preferred method is via Ethernet Connection. If not available and using Wifi - move computer as close to the Access Point / Router and disconnect all other devices connected to Wifi. Want the maximum bandwidth for the computer being upgraded to Big Sur.

Totally agree with @Old Toad :- ))

The Time Machine Backup for the reasons presented by Old Toad and - How to Revert to Previous macOS. It could be invaluable should things go sideways. As for the Clone to External Drive - personal preference. It too can save a lot of time reformatting the drive and starting from zero. The difference between TM Backup and Clone - the Bootable Clone can Run a Full Version of the OS before the drive fails, corrupted etc.

As for Off Site of either TM Backup and / or Clone - that too might be more for the Mission Critical Stuff and less so for general users. Personally - have A Bootable Clone Off Site and am a General User and nothing Mission Critical at all.

Good questions and thank you for the time to asking.

i always recommend keeping your machine fully up to date. i have not encountered any problems and have been using big sur since the launch date. as far as reading lots of people having issues with big sur, i believe firmly that it has to do with this old analogy:

do something wrong and everyone will let you know. do something right and maybe 1 in 100 will let you know.

FWIW, I have Big Sur installed on five different Macs. I've been running them since the first developer betas back in June 2020. If it was a problem, I would have stopped after installing the first one.

I strongly recommend using Time Machine as an ongoing backup for your MBA. Look at the offerings at OWC (MacSales.com) - excellent quality and reliability, good warranty and great customer support.

Envoy Pro EX with USB-C or USB 3 - best from a speed vs price standpoint

OWC Envoy Pro mini - best for laptops, Small and easy to carry long with the laptop

 OWC Mercury Elite Pro 7200 RPM Storage - excellent TM/backup drives for desktop computers and the most economical.

The TM drive should be about 3 times the size of the drive you're backing up.

Welcome and Thank you too !! :-))

Do keep us posted on the progress - if time allows.