I wanted to second Pika's concern about clogging filters. I once camped in the Superstition wilderness during a rain storm. It was nice to be in the desert and not have to worry about water, but all of that new run off meant the water was all very murky. It was nice to have a filter that was easy to clean (I think we also had an MSR) compared to gravity filter. We would pump half a liter, pull out the filter, clean off the layer of silt, rinse, and repeat.