Hi Mouse
this isn't a reply directed at you just a reply in general. I got rid of my gravity filter in - oh 1988 I think, because it was too slow. If I need water I don't have time to wait on a system that cannot be pressurized. To me the hanging filter concept is more for around a cabin. I have no idea how the new ones work, but since you only get 1/2 PSI per foot of water, you'd need a filter element about 20 feet below the reservoir to filter efficiently enough to make up for clogging by particulate matter and back flushing would be hard. Ceramic filters can break if they freeze, like being left out over night in the Sierras to give you morning water. I really prefer a pump type and I like my PUR hiker, as I can get a quart of water in a minute and continue hiking.
Jim YMMV