Can I easily disable the post-update splash page telling me how great the latest Firefox is (or something like that)? I use developer edition to test Firefox compatibility of my webapps, I seem to get that a lot, and I really don’t care about that marketing.

On the contrary, there is no option that says “Stop bugging the user with ads for Mozilla.” They keep coming back with another form of showing up (button in the top bar, label on the new tab experience, new tab experience itself, Mozilla login…) and you have to disable it again. It’s like spam when they use several Mailchimp accounts, reupload your email and tell you “but it’s easy to unsubscribe!”