One point to consider: Aqua Mira isn't bleach, but rather chlorine dioxide. It neutralizes the bad guys by oxygenating your water, but is rendered largely inert by this process and won't negatively affect gut flora. A.M. also works passably well on reducing unpleasant taste and odor, although it can impart some of its own if mixed too strongly for a particular water source (for example, it tastes awful when added to tap water in a glass at home due to having so few dissolved solids to work on). There's a bit of a learning curve involved, but in my experience chlorine dioxide can be an effective primary method of water treatment in the Southwest. This, not in spite of notoriously foul sources like cow tanks and turbid runoff, but rather because of them, and the way filters tend to clog and fail under such duress.
I'd just add that filters are only as effective as their rated porosity is smaller than the cooties trying to pass through. Their effectiveness can also diminish with use, especially as they begin to clog, decrease in performance (harder to pump) and become more prone to internal damage. Cross-contamination of inlet and outlet tubes is also an obvious concern during storage. You'll probably get at least a few cooties (not getting into the technical jargon on that one) into your gut, at which point it's down to survival of the fittest (good cootie vs bad cootie).
Many hikers like filters and dislike chemical treatment, or feel compelled to carry both for contingencies. I'm just here to say that Aqua Mira is all I've ever used on the AZT and GET, I've treated lots of crappy water and never gotten sick. Prior to using A.M. I'd hiked other long trails that feature nicer looking water, on average, and always got sick at some point, regardless of water treatment method (filters, iodine, Polar Pure, bleach, grapefruit seed extract, the works). At this point I'm a full-on chlorine dioxide believer and can't see going back, or moving on, unless the status quo somehow changes for the worse. YM, of course, MV.