If I was using a water source where there was a large amount of silt I would purchase a collapsible sink fill it with water first and let it sit for a while to let the silt settle to the bottom before pouring it into the filter bag, this will cut down on constantly cleaning the filter. This method takes a bit longer for setup but evens out over time.

I've used this filter with murky river water, but not water with a lot of silt. I would imagine that--with lots of silt--you'll just need to clean the filter more often (just like you would with other filters). There is a thin mesh filter before water gets to the actual filter, and this catches most of the larger debris. On a long trip like that (with that many people) I'd make sure that you have numerous filtration systems. For example, if I were going on a 4 person, 2 week trip, at a bare minimum I'd have the Katadyn Base Camp, an extra filter for it, and at least 1-2 hand-pump filters. On a raft, weight and size are less important than on a backpacking trip, so I would rather be over-prepared when it comes to ensuring that there's no chance that I would need to skimp on fresh water. Other than an injury, there's no other thing that can sabotage a trip like running out of fresh water can.