If you use Firebug a lot, Do NOT do it.. Firebug sucks on version 15, just wait for the Firebug guys to update
I sent a message about this to them. Hope they take it under consideration.
Better idea: Switch to Google Chrome.
Chrome is my soul mate..no complaint yet for me
Was working on a CSS 3d project, worked perfect in 14, z-sorting now buggy in 15. Damn It!
You may just find that the Developer Tools in Chrome are a good alternative to Firebug. Worth a try in my opinion.
After i try google chrome Developer Tools i never get back to Firebug in Mozzila