I appreciate the flashy experiments like Firefox Command Line but there's little chance of them entering into my everyday workflow unless I have the chance to learn them properly. I won't get the chance to learn them properly until I reach for Firefox as my main development browser.
On another note: The Chrome Network panel is invaluable to me and streets ahead of the Firebug Net panel. I find it hard to explain why I prefer it as the features are fairly similar, but the experience is much better. Maybe it's about the layout and clarity vs. density of information.
Two things that still stand out as lacking when compared to Chrome are the JS console output and the Net panel output (really hate those popup windows).
But these things can be ironed out. Well done for getting Firefox moving in the right direction.