[onion2k]

Nobody is going to switch from Chrome to Firefox if the UI is radically different.

You could easily make the argument that no one is going to switch from Chrome if Firefox is very similar too because there'd be no good reason to.

Guessing what users will do is a waste of time. You have to do experiments and actually measure it.

[pygy_]

Anecdata:

I switched back almost 10 years ago (because Google creeps me out), and the UI differences made it much harder.

I ended up tweaking firefox with extensions to make it look and behave like Chrome as much as possible, then gradually turned it back to the default UI. It made the switch far more pleasant.

[Causality1]

Frankly I would, and do. I use mobile Firefox for its features like adblocking extensions and reader mode but it's always a less pleasant experience than mobile Chrome because it's less snappy and intuitive.