Plus Firefox crashing is a huge downside.
As for privacy implications, there's no reason to believe Google does anything inappropriate, and I rather like having my internet experience tailored based on past behaviour.
To each their own I guess.
How do you get Firefox to crash? What does about:crashes say? Did you report the bug?
Also, pretty much anything that's Javascript + WebGL runs like shit in Firefox. Emscripten demos are good though. But Emscripten runs better in Chrome than JS+WebGL in Firefox.
Compiling all those shaders is rough on any browser, but only Firefox gets its entire UI blocked. Even Internet Explorer manages to isolate the jank to one tab.
Sadly Firefox 39 (nightly) still has no real multi process support. There are only two processes, the main process holds all tabs, the single child process "plugin-container" holds all plugins (Flash, Acrobat, etc.). It's a bit disappointing to see such little progress since 2010. Hopefully Mozilla's Rust based Servo engine comes to the rescue soon and replaces gecko and its old XUL (XML based UI framework) with Servo and an HTML5 based UI (like Firefox OS).
I use Firefox as development browser because of Firebug and and the new developer tools. Working with dozens of tabs open for days is only possible with IE11 and Chrome.
That is incorrect. There is one plugin-container for each plugin module. All Flash instances share a single plugin-container, all Acrobat instances share a single plugin-container, and so forth.
As for the e10s content process, for the moment there is only one content process. The plan is to get e10s working well with the one content process, and then start scaling that up to multiple content processes. Nightly is a bleeding edge development channel, after all.
Another interesting thing you can do: click through from about:crashes to your crash report. Then click the "more reports" link. You can see if your crash signature is rare or if you have one of the currently "popular" ones. If a lot of other people are crashing with that same signature, there is probably a bug and developers are probably discussing it. Again the most useful thing you can do is figuring out how to make that crash happen consistently and adding steps to reproduce it to its bug.
If that's the case try using 64 bit builds.
Instead, I've switched to Disconnect search. They proxy searches and claim to do so anonymously. So at least I'm not directly contributing to Google's profile building that way. It does add a second or two latency per search, which can be annoying.
FF switched to Yahoo, and I'm just amused at how bad it is. They even open results in new tabs by default, a lame trick used to try to accidentally keep people on your site.
It's unfortunate, but Google really does dominate in search.