I have had a first need purifier (pump/gravity feed) for the last 9 or so years. It is BY FAR the best pump style I have used (and the only small pump purifier that I know of). I also have a MSR MIOX and have used several MSR and Katdyn ceramic filters. A buddy of mine has a Berky and to be honest, I was a bit underwhelmed by it. About the only role for such a unit is at a stationary location like Sar5 speaks of, otherwise, waaaaaaay too slow (as in .5hr to do less than a pint) heavy, and bulky for anything BOB related IMO.

Boiling (or distilling even better for heavy metals) is about the best/most simplistic option, but is fuel heavy (may or may not be an issue for each AO, and distilling is even more time and fuel consuming).

Bleach can also be used, is cheap (think a few drops per liter) but losses some punch after about a year of storage

Iodine is also always an option and if you go with the tincture, you get a two-fer for an unbeatable low price and KISS factor.

As you said, two is one. Grab a purifier and a pump of some kind, and next time you are at WalMart pick up a small bottle of iodine for $1, have a metal pot for boiling and you will have your basses far more than covered.