One thing to note is Chromium’s integrated debugger is a lot faster than Firebug. I haven’t used it extensively but if it can break at breakpoints and introspect objects without getting screwy I might end up switching. I really like firebug but lately it has become dog slow. It usually takes a couple of minutes of waiting for each frame of data to be processed and displayed while under Chromium with their debugger on, the slowdown is noticeable but not significant compared to when the debugger is off.
UPDATE: Chromium’s debugger is probably faster because it doesn’t actually do anything that I can see. It displays scripts but doesn’t actually break into the code[read this post in: ar de es fr it ja ko pt ru zh-CN ]