Sorry, I feel obliged to comment on the inclusion of an axe with a pack that I have said needs to be "light & fast".
I think an axe is a very useful tool. On a true "get home" trek I would not expect to use it for chopping trees, which I think would be a poor use of time and energy. But it does make a great tool for:
hacking your way out of somewhere you have become trapped (such as a building you holed up in for the night, which has been damaged by an aftershock during the night)
Passive defense (seriously dude, who attacks a guy carrying an axe? Nobody, that's who). As mentioned there are reasons not to openly carry a firearm, and without SOMETHING formidable visible you look like an unarmed supply depot. And I'm not about to bring an axe to a gun fight, but bring an axe to a knife fight, stick-fight or fistfight? I'm down with that.
It's just such a useful tool, I would make room for it on my pack. By choosing the scaled down "boy" axe, I get the benefits of the long handle (reach) but save some of the weight over toting a full-sized axe.
The one thing worse than defeat is surrender.