I can tell the difference in daily usage, where I would have to restart Chrome every day or two on Linux because of excessive RAM usage (I do keep a lot of tabs open, and simultaneously run IntelliJ IDEA among other JVM programs/docker containers), and I don't have to with FF 54/55+ anymore. Each tab in a new process became the default in 54/55 as long as all of your extensions are updated. I haven't looked back since.

I have tried switching away at points before this, and something would bring me back to Chrome/Chromium, but not this time.