IE9 supports the three modes (7 8 and 9) that you need and 98% of the time they mimic the native versions of each mode pretty well. If you're still testing for IE6...well....stop 
With regards to IEs developer tools - I didn't realize it had any (sarcasm). Up to IE9 they're absolutely useless so I simply don't use them. I do all my building and debugging in chrome and then check IE in compatibility modes to make sure I haven't left any trailing commas.
I've switched careers...
I'm NO LONGER a scientist,
but now a web developer...
awesome.
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