[mike-cardwell]

"Tools to permit you to wipe out your HPKP mistake would be usable by attackers, though."

I meant tools to prevent you from making the mistakes in the first place, not for fixing it after the mistake.

The non-enforcing mode doesn't help. When I talk about mistakes, I mean things like losing access to your cert or timing mistakes in rolling the cert. If I roll it out today, it will be fine today. It will probably fail at some point in the future though, and fail hard, unless I follow very strict processes.

HSTS is considerably less dangerous. Once it's set up, it will continue to work without you having to do anything extra. HPKP on the other hand requires you to actively consider when you generate new certs, and when you add extra HPKP headers to your responses, and when you roll the certs etc.

I can change my CA or generate a new key today on a whim, because I don't do HPKP. If I did do HPKP, this would require considerable thought and preparation in advance.