To focus in just on whether to use the adaptor or just go without it, try it both ways, and see if you prefer the open draw of no adaptor or the slightly more focused draw of the adaptor. You can go back to the balsa filter in an instant if you want, but I prefer the adaptor. I think you might encounter a few pipes where the airway has more turbulence in the airway without the adaptor, which might cause moisture and/or noise, but mostly I think it is strictly preference. Many Forums members state they smoke both 6 mm and 9 mm filter pipes without the filters and are perfectly happy with them, and no adaptor. Just see which you like.