> Using the shim for dual-booting was a pain, not least because Microsoft updates periodically removed it.

I've never had this, but I guess if you have it installed to /efi/boot/bootx64.efi it would be no surprise that Windows updates replace it.

So when dual booting you shouldn't use bootx64.efi for this reason and I'm pretty sure most distributions don't and instead install to /efi/<distribution name>/