Personally, I think that console could do some work. Chrome console is top notch, and there is too much noise in FF version, with CSS and other stuff.
EDIT: Another thing, there needs to be a font shape difference between input and output. Basically, you should be able to tell if something is input or output without looking into the arrows to the side.
What language are you guys writing Dev Tools? I'd love to be able to help out, but I'm not too great with C++?
Just any property that has a preset number of values show up as options as you type. The difference is that Chrome shows a dropdown list while with Firefox you have to sort of remember the values as it does an autocomplete. I see no reason Firefox couldn't offer the dropdown since it clearly knows the possible values.
By the way, I tried the same font thing in Chrome and it responded the same way, no font list. You can see a similar behavior with color, for the value it shows possible colors by name. Start your color with # and suddenly there's no options. If there are too many possibilities to list it doesn't list anything.