Wow, I had no idea YubiKey offered that mode of operation. I had assumed it was purely used as a OTP. Do you know of any documentation for it?
I had a blog post some time ago - https://varamashvili.blogspot.com/2012/09/using-yubikey-with...
I should note that currently i'm thinking to migrate to OTP and use brain-string (password that i remember) for filevault and mac login. I will try using OTP for sudo, maybe keychain, will try to add gpg subkey there and see how it'll go.