- You can't disable the browser cache from FF devtools, which really sucks when you are trying to debug a broken redirect.
- When inspecting an element in FF devtools, :before and :after CSS properties will not be shown. I wasted many hours debugging a CSS refactor because of this (imagine going up the DOM, comparing computed CSS properties until you reach the root). Both Firebug and Chrome devtools will show :before and :after properties.
I think Firebug and the Chrome devtools are comparable in quality.
Can you even debug a web worker with Firebug? How about SourceMap support? The times when I've had to switch to FF devtools have been pretty painful. The profiling and tracing tools in chrome also seem lightyears better.
The responsive design view is very handy. It switches the size of the view port without changing the size of the whole window. I still use firebug most of the time, but there are some issues with firebug you have to be careful of. See this post for an example http://perfectionkills.com/understanding-delete/#firebug_con...