Is there any problems at all if I just keep the legacy format?
achow101 mentioned legacy wallet support will be dropped on Bitcoin Core 27.0[1]. If you decide to use that version in future, you must convert legacy wallet to descriptor wallet.
Also this always sounded more secure to me even if you required to make backups each time you generated new addresses to keep them:
The original Bitcoin Core wallet was a collection of unrelated private keys.
I don't see how it's more secure unless you assume master private key alone could be brute-forced or stolen.
[1]
https://bitcointalk.org/index.php?topic=5469585.msg62962204#msg62962204I see a problem with this:
This is one of the most noticeable differences. With descriptor wallets, you cannot export the private key for one address. This is because a child private key combined with the parent public key can be used to compute the parent private key (and hence all other child private keys). This is a risk inherent in BIP 32's unhardened derivation. As such, descriptor wallets disallow the export of child private keys in order to mitigate the risk of accidentally exposing the parent private key.
But you shouldn't be exporting individual private keys anyways. The wallet does not use just one private key, so having an individual child private key is really not that useful.
If you want to export a private key that contains a reasonable amount to carry on a phone and import it into the phones Electrum wallet or whatever, then with the new format you wouldn't be able to do this, because apparently you will not be able to export individual private keys due the new format.
What I've read is that it makes watch only wallet creation much easier.
Also can you finally have a seed that generates the wallet safely like on Electrum if on a worst case scenario you lose your wallet file or if you lose the wallet files you are done for?