great point. I haven't read about this experience, but I believe you. I know that there are different kind of animations that trigger different reactions (like, fade in text is different from things shifting on the screen).

Please, track Mozilla progress over the next months if you have the time. We're drafting a workforce to start the UX updates and I hope we'll get voices like yours well represented. I'll make sure to post about it on HN once we begin.