The Nexus 7 out shines the Kindle Fire, not because the N7 is more powerful, the N7 beats out the Kindle Fire because it isn't crippled.

A Kindle Fire with CM9 on it is only worse than the N7 because CM9 is buggier and ICS is uglier than stock Jelly Bean.

EDIT: I ditched my Kindle Fire for a N7 before Jellybean was available for the Fire.