I'm a big fan of the Maxpendition product line so this may be a little baised.  As a primary bag you may want to look at one of their other products (I have their Monsoon Gearslinger as my EDC bag & I wouldn't trade it for anything) but as a backup it'd be really hard to beat.  This bag turned out to be a big help on two recent trips.  A few months ago I took a trip were space was really limited & I couldn't take both a regular suitcase & my Monsoon but I thought I might need to do a bit of walking. Maxpedition to the rescue.  This bag packs down pretty small so I managed to find a place for it in the suitcase and when it turned out that I did need it, out it came, in went the water & other supples & away I went.  On a recent hike a friend of mine forgot his pack.  I've been leaving this bag tucked down in my truck console so I just pulled it out, unfolded it and after a quick stop for him to buy some water & snacks we were good to go.  I am so glad I picked up this bag.