David I have a convertor but to be honest I usually just use cartridges. I actually bought it in extra fine, loved it, but it kept skipping an stopping and actually didn't write that well on my Leuchtturm journals. The fine works great. I confess I have never used the convertor with the fine - cartridges are good and so easy. I'm too scared to go the eye-dropper route!
I really like the compact design that I can stick in my pocket. I'd like to upgrade to one of the metal cased ones (Brass or aluminium).