The 2/2 requires two separate xpubs, where the single seed requires one xpub. For individuals, 2/2 just makes things more difficult when signing transactions and recovering. Frankly, splitting the seed in two parts in the first place isn't something one should labor with. This type of complexity is unnecessary unless you have an exceptional reason.
I'm of the opinion individuals shouldn't use multisig to begin with. If they do, it should be 2/3 multisig where a custodian (3rd party) holds one of the private keys along with all 3 extended public keys — which means yes, they can see and monitor all your transactions. Because like I hinted at above, people seem to forget that with 2/3, 3/5, etc, if you lose one of the private keys, and don't have the wallet file or extended public key saved somewhere for that private key, your bitcoin is lost forever. Because you need all three public keys to construct a valid 2/3 multisig transaction. With this setup, you have shit saved and stamped all over the place, you have all these different singing devices, it gets unmanageable for something that's quite simple. There's a better way.
I'm of the opinion individuals shouldn't use multisig to begin with.
I disagree with this. I'd say if an individual has a large amount of their net worth in Bitcoin they should have it in a multisig. I don't have any issue with using a custodian, but if you have someone you trust to hold onto 1/3 sig then you can go that route too. Ideally you have someone that also has money in Bitcoin and they can use one of their signing devices in your multisig. You want them to use one of their sigs because they also have an incentive to keep it safe.
For the backup of the xpubs (I think the descriptor is actually want you want) I think you should just throw that in your password manager. It's semi-secret and isn't the end of the world if someone got access to it. If someone got access to all your passwords in your password manager they could do a lot of damage, certainly more than if they just had your xpubs.
There is also the seedhammer if you want to backup your descriptor. If your Bitcoin is a large % of your net worth buying a seedhammer shouldn't be that big of a deal. I also think Bitcoiners should focus on setting up a Bitcoin Citidal near them and one of the features they should offer is a seedhammer.
There's a better way
What is the better way?
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Occam's Razor. And realize what 128- or 256-bits of entropy means, trust the math.
A 2/3 custodian is fine. Trying to retain all that information yourself is not. What's also strange are the people who refuse to backup their seed by memorizing it as well, which in real world cases, would prevent 99% of self-custody losses. Literally a once in a lifetime requirement. Instead we get a parade of ever more difficult custody schemes. Good news is that hybrid self custody, scripting, and a possible vault-type BIP could end the self-custody question for good.
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Occam's Razor. And realize what 128- or 256-bits of entropy means, trust the math.
Occam's Razor just means the simplest option is usually the better option; The usually matters. I'm not sure what you mean by the entropy sentence. The difference in 128 vs 256 bits of entropy only applies when you think someone might bruteforce their way to getting your private key.
Literally a once in a lifetime requirement
No it isn't, what happens when you have a brain injury that makes you forget your mnemonic phrase? What happens when your forget it as you age since as you age your memory gets worse.
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Splitting your seed decreases entropy.
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