When the "free web" is no longer just lip service from Mozilla I'll consider it.
My guess is this: https://blog.mozilla.org/en/mozilla/we-need-more-than-deplat...
Firefox's only selling point right now is "we aren't chrome (yet)" and if I won't fall for that line of thinking at the ballot box I'm certainly not falling for it here.
All they have to do is be what they say they are. At least google doesn't pretend to not be evil anymore.