[euank]

The firefox instances have completely different processes, settings, etc. Everything. Chrome, unless I'm mistaken, does not go that far.

For example, one of my main uses of multiple-profiles is that I have a different profile for every proxy I use. I can launch a firefox profile that's proxied side-by-side with my usual firefox (aside, the firefox proxy settings are exposed via the UI, unlike chrome).

Chrome, I'd have to run "google-chrome-stable --proxy-server=$proxy" and then, again unless I'm mistaken, all accounts will use that proxy server. That, by itself, is a deal breaker.

I'm not familiar enough with chrome's settings and so on to say what does and doesn't leak; I could be completely wrong on all of this, but I suspect I'm correct.

Edit: On looking more, Chrome's does look more complete than I thought. The proxy bit still is a dealbreaker for me (well, and I'm adverse to logging into a google account), but I retract much of what I said.

[barrkel]

Have you tried FoxyProxy Firefox extension?

[euank]

I haven't used it in a long time, but I did use it at one point.

It's just not as good security and privacy-wise. Using proxies on/off on one profile, as it encourages, results in any tracking cookies seeing both IPs having the same tracking data, and thus your proxy has lost some of its privacy.

I also run entirely different extensions when I'm going for privacy vs fun browsing vs banking etc etc.

If you just want proxies to get around some region restriction and don't really care about the privacy or security aspects, then FoxyProxy might be fine.