Indeed, IE6 is a ECMA killer. That's because it only implements like 70% at best of the standard DOM-processing functions, not to mention there are DOM elements still a stranger to IE6. IE7 does somewhat better though it's still a headache. (I'm not even going into CSS-rant)

And yeah, I'm already negotiating a stress bonus on projects involving JS apps and IE6. Kudos to the DebugBar team, it's a long way to Firebug, but it's a damn good step.