I too recently tried to switch back from Chrome to Firefox, but gave up. Lots of tabs highlighted the single process model. I love Certificate Patrol. Ctrl-W closes tabs with Flash just fine in Chrome, but required a click outside of Flash first in Firefox. And while Chrome went it alone with Pepper, at least they did something to really isolate and contain Flash. The final straw though was wanting my vertical space back - Chrome's tabs in the title bar is excellent at that. I eventually discovered that you can't do it with Firefox on Linux, and the relevant tickets were full of nasty comments about how Firefox should never do that. Oh well.

I originally switched from Firefox to Chrome because of some web code I was developing where I accidentally made the server send unlimited data (it was supposed to send one line of status information every 15 seconds - I forgot the sleep). Firefox's single process model resulted in a hung browser while Chrome let me find the cause.