Last year, I went out on a limb and bought the MSR Hyperflow. It uses glass tube technology to filter the water. From what I read this has been used in commercial treatment plants for quite a while and this is the first backpack implementation. It can be cleaned in the field by switching a couple of valves and backflushing. There is a concern with freezing - apparently if the thing freezes, the tubes can shatter, rendering it useless. Anytime I've been concerned about this, I make sure to pump it dry and keep it in my sleeping bag at night. I've had ZERO problems with this filter and really like it. It will fill a liter bottle in about 1/3 the time of any other filter out there (around 19 strokes of the pump). Weight is minimal, as is space required. I think the whole thing is under 9 oz and it is about as big as a hot dog bun. You'll never beat the weight of chemical treatment, but I find this filter is a good option. Small, lightweight and no nasty chemical taste. I'm very happy with it. It trimmed quite a bit of weight and space from my pack. Good luck!