Got the update for v. 83 yesterday and I decided to enable HTTPS-only mode and it works fabulously. It does “break” some sites but it also saves my butt on certain sketchy sites that have certain pop ups. Firefox immediately blocks them even when No-script or adblock can’t. Really cool.
Of course, it’s only a matter of time until these sites catch on and start using TLS/SSL on that traffic… until then, it’s looking cool.