You might look at the MSR Hyperflow, if you haven't already. A bit lighter than the Vario. I've read of problems with it, but I've been using one for over a year without problems. They say it's field cleanable, but it's a rather fiddly backflush: take it apart, reverse two small (easily losable?) valves, then reassemble it, pump clean water through (upside down and backward), the take it apart, put the two valves back the way they were, reassemble, and hope for the best. So, I carry a spare filter element (one or two ounces) and switch them out if the first one clogs. I do the backfilter thing with it when I get home and have lots of clean water.

Whatever filter you choose, take along a backup method (mine is 10 or 20 Potable Aqua chlorine dioxide tablets that live in my first aid/repair kit.)