I own and smoke several (with the 9mm "European" type carbon filter) so obviously like them, (yes, I'm a barbarian!). Regarding passing a pipe cleaner through them, as the filters need to dry out between uses, I remove them once the pipe has cooled. I can get at least two and sometimes three uses out of each one, depending on how big the bowl is and what I've smoked in it, (OK, so I'm a cheap barbarian!). I would not recommend leaving them in the pipe, once smoked, for extended periods, but that's just my experience. Even if you use them just once, I'd take them out when the pipe is cool. But then, I "break down" all my pipes, regardless of type, between smokes to let them air out. I haven't noticed any of the bits loosening up, and perhaps over decades of use they might, but at my age and health, (and the fact that SWMBO has recently taken out several large life insurance policies on me :suspect: ) I'm probably not going to live long enough to find out.
I also use the Savinelli balsa filters in the 9mm pipes, and they filter the smoke much less than the carbon filters do, but really keep the moisture level down, which I like. I find them best with the straight Va's and lighter Va flakes. Depending on what tobacco I'm smoking and how I feel at the moment, I may use either of the 9mm filter types in the pipes, smoke my Kirstens, smoke a MM cob (with the 6mm paper filter in it) or smoke one of my non-filter pipes. They all have their advantages and nuances. Love the variety and choices we have.
My recommendation is to buy several, try them, and if you don't like them, sell them to me really cheap! :mrgreen:
Natch