I haven't bought or used a cartridge converter pen very much for about six years now. The last one that I used regularly was a Duofold Centennial. Even back then, I did note that on the rare occasion that I used a cartridge in place of the converter, the ink flow seemed smoother and generally produced a better writing experience. These days, I wouldn't consider buying a pen if it was offered only as a cartridge converter, and piston fillers obviously don't suffer this problem. Any one else have any thing to say on this topic?