I used both the MSR Autoflow and the Platypus GravityWorks within the last few years, and found them both easy to use and to backflush. The filters are identical; the only difference is the reservoir materials and the "clean" bottle fittings. (The fittings had nice covers for limiting cross-contamination.) I liked the wide opening for scooping water; being able to re-seal it securely allowed me to use it to carry water to a dry camp. I was using a 2-liter "dirty" bag with each; I'm wondering if 10 liters might be a little awkward to lift and carry when you're perched with one foot on the muddy bank and the other on a moss-covered wet rock while you fill the bag.

Backflush is easy: just lift the clean bag higher than the outlet on the dirty bag, and let clean water flow backward through the system. I never had any problems with this working. The dirty reservoir in both systems is nicely designed with an inch or so of space below the outlet where sediment and other crap can settle out, and not get sucked into the outlet. Very thoughtful, and something you can't do easily with the Sawyer.

In the end, I went to the Sawyer Squeeze for the simple reason that I got tired of fooling around with the hoses on the MSR/Platy setups (I use the "cleaning coupler" to attach the clean bag.) I also replaced the Sawyer bags with Evernew collapsible bottles - including one that has a wide opening on the end for scooping up dirty water.

However, I don't believe you can go wrong with the MSR Autoflow or Platypus GravityWorks system.