I don't know that the YubiKey support will make a huge difference, but user namespace support is huge. Running services as root -- especially important things,

I don't know that the YubiKey support will make a huge difference, but user namespace support is huge. Running services as root -- especially important things, like web servers, or virtual machines, or containers -- is a big no-no in security. Kudos to the Docker team for proactively fixing a complaint I've heard a few times from security-minded people!