it’s like 20$ on amazon for a new filter replacement. I read a write up on the backpacking light forums, and I think they basically just slow down and then eventually stop. the water sources I use are almost always clear and clean. I have seen videos of the RapidPure filtering some gnarly water without much slowing down.
the idea of the filter just plugging up would probably scare some people away and I do carry a Steripen for day use, as well as tablets as an end all. from the way the filter is designed though, I can’t see it just stopping flow like the sawyer does unless you filled it with mud. I read the filter is rated to thousands of gallons, but again it depends on water source. I plan on replacing the filter once a year unless I have to filter some really gnarly shit, then I might replace it for good measure and to keep up flow rates.
had it mostly freeze a few weeks ago turkey hunting and I asked the company if I need to replace it and they said its good for a few freezes due to the nature of how the filter works. so, that’s a bonus.