Agreed on separate windows for distinct topics. For that, I find the FireTitle extension invaluable:

https://addons.mozilla.org/en-US/firefox/addon/firetitle/

You can flexibly add text to the title bar of each window to name the window as you choose. These names show up in Aero Peek etc. to make switching between windows effortless.

TreeStyleTabs, FireTitle, and a few other FF extensions are what keep me firmly in the FF camp. Its extensibility is the best of all the browsers IMHO.