I hear you on the control thing. You mention you are a power user above so my two cents is that likely puts you outside of the user base Mozilla covets. In the last couple years, the words "Firefox" and "power user" went hand-and-hand but I'd wager Mozilla would trade customer bases with Google in a heartbeat.
FWIW, the Developer Edition feels pretty lean and mean. I haven't tried since I am a web developer, but it looks like you can remove most or all of the parts that make it web developer-y if you are so inclined.
"You mention you are a power user above so my two cents is that likely puts you outside of the user base Mozilla covets."
Mozilla's business model needs users who can't figure out how to turn off Yahoo search. That pays for their new Firefox offices on the waterfront in San Francisco.[1]
I've ran Nightly and Aurora (which is now Developer Edition) for a while but extensions/themes broke more often than I'd have liked because there was too little time for extension devs to update their extensions in case incompatible changes were introduced.
FWIW, the Developer Edition feels pretty lean and mean. I haven't tried since I am a web developer, but it looks like you can remove most or all of the parts that make it web developer-y if you are so inclined.