The main reason I went with the VersaFlow was that it came in a bundle with 2 Vecto 2-liter containers on the CNOC website; at the bundled price, one of the containers was essentially free.

Functionally, the VersaFlow is pretty much the same as the Sawyer. However, a few of the design features simply fit my "style" better - i.e., are more convenient to me. (Don't underestimate how much your personal preferences influence "convenience.") I like that both ends of the filter have female threads, so you can attach a container to each end without a "coupler." The input and output holes on each end also have little caps that fit over them when not in use, greatly reducing the chances of cross-contamination of the clean-water outlet and also preventing the filter from draining into the pack pocket and, eventually, down your leg. It also has a little window on the side that helps you visualize how "dirty" the filter has become and prompts you to backflush. (Oh, yeah - you backflush by squeezing a container of clean water, not by using a little syringe with a tenuous connection to the filter.)

But, if you prefer the Sawyer, you're getting a similar filtration system - and the CNOC containers are compatible with it.

The CNOC Vecto and Vesica containers are a whole lot easier to deal with than the Sawyer POS bottles. The Vecto opens at the bottom, so you can "scoop" water easily, then seal and attach the small-neck opening to your filter. (You can't really "scoop" with the Sawyer bottle, and need to find a small falls you can put the bottle under to fill it.) The open bottom also helps dry them after a trip.

Any filter will eventually clog into unusability, so don't forget to take some purification tablets as backup. For some reason, filters only seem to fail during a trip.