Not all pipes are tapped for filter use. I avoid them.
Filter Pros:
* Moisture abatement (that is, until the smoker leaves them in for so long they solidify and stop working)
* Good feeling about smoking (I'm healthier because the filter is trapping what I think is all the 'bad stuff'!)
* Hip 'n' cool in Germany (...they're all doing it, so it must be the thing to do)
Filter Cons:
* They're a pipe tampon. If you don't change them out frequently, it's a disgusting mess.
* They filter out almost nothing except flavor (they aren't "healthier"--it's smoking: it is what it is)
* They stink, unless they're brand-new
* They hinder new smokers from learning nuances of smoking pipes by affecting draw, moisture content and covering up tobacco flavors--all keys as to how to smoke. (Square training wheels).
And on.
There's a big difference between the rolls of paper known as the "Medico" filters and the balsa wood triangles available for Savinelli pipes. While most guys swear off the paper Medico filters, there's quite a few who use the Sav wood filters and actually enjoy them. I'm not one of them. I won't even buy a pipe that is set up for a filter, except cobs, which can be smoked without them without a problem. Otherwise, a filterless filter pipe is another ball of wax to contend with (and can be a pain in the arse).
Just my take.
8)