The ULA Amigo Pro filters about 1 liter per minute, which is pretty fast. Before I got it, I kept putting my lower back out bending over the water source using a pump filter. Very painful! Pump filters are also several ounces heavier. The back problems were why I switched. It's really nice to be able to do something else (putting up the tent or admiring the scenery or even taking a cat nap) while your water filters!

I tried the Aquamira Frontier Pro (why are they all called "Pro"?) as a gravity filter last summer. This was per the video from Jason Klass, which recommends using Aquamira or Katadyn tablets to kill "the little stuff" (bacteria and viruses) and using the filter to get "the big stuff," by which I assume he means protozoa. The filter itself takes about 12-15 minutes to filter a liter. Add 15-20 minutes for the tablets to work in addition to 15 minutes for a liter of water--that was far to long to wait for a decent drink! The Aquamira website cagily doesn't mention the size of the filter, but another source gives it as 3.0 microns. Per the CDC, a 1.0 micron filter is needed for giardia and crypto cysts, so it's questionable that the Aquamira Frontier Pro will even filter out those.