Thanks for the description of new products. Regarding the AutoFlow used as a gravity filter...Do you have any experience with the Katadyn Base Camp filter? ( Katadyn website, REI description).
It sounds like the AutoFlow may filter a little faster, but to be honest, I don't know how much that matters with this type of filter.
I'm a fan of the bump! To answer your question, I haven't used the Base Camp Filter. I have seen it work and understand that it filters 0.5 liters per minute. I also know that it can't be cleaned in the field and is heavier (17 oz. compared to 10.5 oz for the Autoflow).
The great thing with the AutoFlow is that it is well thought out. I have always been either a pump or a chemical user because I felt the complication and wait time of a gravity fed filter just wasn't that intriguing to me. However, after using the AutoFlow system I am convinced this is my new method of treating water. That fact that it can filter at 1.75 liters per minute and that it is light and packable makes it almost too good to be true.
To answer frediver's inquiry about the prefilter: one of the great things about MSR, in my opinion, is that they really engineer a solid product right out of the gate. MSR has had this technology for as long if not longer than Sawyer, but chose to take their time in creating a world-class product based around the Hollow Fiber Technology. We have found that companies that rush product to market miss the boat an many key elements. In this case the prefilter. MSR uses a prefilter similar to their pumps (70ish microns) to make sure sediment doesn't effect the life of the filter. MSR has also created a bag that allows much of the big chunks to settle in a "pocket" so, after the bag is emptied, the dirt is collected on the bottom of the bag. Sediment is not a problem with the AutoFlow.
The other really huge benefit to the new Hollow Fiber is that it can be cleaned by backflushing. I haven't played with the Swayer product at all so I don't know how easy or difficult it is to backflush, but the MSR is super easy. All that the user needs to do is reverse the flow by holding up the bottle of water higher than the reseviors for a few minutes while the clean water goes back through the filter. My experience has been one of amazement as I can see the dirt be cleaned out of the filter almost instantaneously. This allows for more longevity and better performance. Both the MSR AutoFlow, HyperFlow, and the Platypus ClearStream are truly innovative and revolutionary water treatment products for the backcountry which will elevate the standards of field performance.