My primary filtration device during my trips to Ecuador has been the Katadyn Orinoco Water Purifier, it is easy to carry (but heavy) and fill. It provides 90% of my water needs. I have also used an MSR pump filter when I need larger quantities of water and the STERI-PEN for a quick glass of water and to provide sterile irrigation water for wound care. I was quite comfortable that all three have provided me with biologically clean water.

Since I have not had the chance to use the MSR MIOX in the field I am hesitant to make a recommendation. However, I will give you some idea of where I am headed. I will definitely take my MSR MIOX on my next trip to Ecuador at the end of July and let you know how it worked. It has several advantages over pump filtration systems in that you can treat up to 4L of water at a time. If you have multiple containers you can treat a very large quantity of water in a relatively short time. The down side is that the water must be relativity free of chemical contaminates. Also the question of battery life and availability maybe an issue to some, as it uses 2 X CR123 batteries. One advantage over my pump, it is much lighter. Finally, as I have pointed out, I really think that this device has greater potential then just treating drinking water.

I did not answer your question outright, but feel the right answer may depend upon where you will be acquiring water and the relative risk from chemical contaminates. Pete