Well, I finally broke down and bought one. For years my hunting partners have owned the MSR MiniWorks filter/pumps so I have used them quite a bit. I never had the need really to buy one nor did I really want to carry the extra pound or so Well, when I heard about the HyperFlow last year at 7ozs and a pump rate of 3 liters per minute it got my attention.
I must admit that even though the MiniWorks are great pumps it's a lot of work and fairly time consuming to pump a couple gallons of water for two guys when "filling up". Especially if you are dog tired. Even just pumping 2+ liters to fill my bladder was kind of a pain. Well, the HyperFlow is a different animal.
I have not had the HyperFlow in the field yet but I did pump some water with it to get a feel. Man, this thing is great. In about 20 pumps/20 seconds or so I filled a 1 liter nalgene bottle and it's very easy to pump. I know a guy who has been using one quite a bit and he really likes it. He says the back pump feature to clean it is really slick.
I will get my hands on one of my buddies MiniWorks and do some comparing but my preliminary first impressions are that this HyperFlow is the hot setup for what I want. That is as long as you keep it from freezing. It says it right on the pump. "Do Not Freeze". Everything has it's trade offs.