As a user whose trust has already been broken by both ISPs and governments, I see no drawback in participating as a user in this public experiment. What you describe as a drawback is a privacy improvement for me.

The DNS implementation used by every non-Tor user around the world today is already subject to warrantless spying by every ISP and government in the world, due to the property known as “cleartext”. If you opt-in to the Cloudflare trial, you are only at risk of warrantless spying by Cloudflare — rather than every ISP — and the US government — rather than every government.

My cellular ISP sells my DNS queries to advertising networks, and my home ISP is wiretapped warrantlessly by the US government. This experiment decreases the chances of the resale of my personalized data to data warehouses and decreases the chances of success of warrantless wiretapping by my government.

I envy those of you that believe you can trust your ISPs and governments.

And lets not forget that their CEO will arbitrarily censor and stop serving people he doesn't like. He's done it before. He'll do it again. Cloudflare has already lost my trust.

In his blog post on that, he said pretty clearly that he doesn't want and should not have this power. https://blog.cloudflare.com/why-we-terminated-daily-stormer/

(Disclosure: I work for Cloudflare.)

But he does and does. And now in the Perfect 10 lawsuit against your company it's biting you in the ass. Now you have to censor everything. Good going.

But in agreeing to spy they would violate their contract with Mozilla.

Presumably, that would make them liable to damages.

Moreover, they will be subject to audits, where such spying is at risk of getting caught.

This is a lot better than everyone trusting their own ISP.