Water treatment question

I have been researching water filters and need some advice. I am taking a group of boy scouts (12) on a week long canoe trip on the lower portion of the buffal river in AR. It is a 53 mile trip with just a couple of public water sources along the way. In the troops gear we have several hand pumps filters(katadyne and msr). We have used these on weekend backpacking trips with no problems but I am looking for a better (FASTER) way. I have been looking at the sawyer 4L system and their point one bucket system as well as the katadyne base camp. I like the thought of the "bag" systems just for the fact they take up less space. What experience has anybody had with any of these systems.

The only one I've used is the Platypus Cleanstream and I was very happy with it. It'll do 4L of water in just a few minutes (I didn't time it but I was surprised at how fast it went). A couple of times the water I put in was pretty murky and it came out clear and good tasting every time.

The Sawyer is darn fast, so long as you get all air out of the tubing and filter cartridge. It's also field-backwashable, which might be a big deal depending on how clear your water is.

Definitely recommended.

Cheers,

ive herd the gravity systems are great for groups.

If you like the MSR, what about the MSR Autoflow gravity filter kit?