Very sound advice.
I have had, and still have, several piston-fillers and ink-sacs, especially older Mont Blancs and Watermans, which perform well. However, piston fillers can go wrong, and when they do, it is usually an expensive process to have them repaired; if indeed a repair is possible. The same applies to ink sacs.
These aren't likely to be major considerations when the pen is in a lower price bracket.
Converters have one drawback that I occasionally encounter, which is they come loose within the pen if the fit is not the best. The same can happen with cartridges, to a lesser degree.
Converters have one enormous advantage for me. Piston pens have usually to be immersed over the entire nib to be filled correctly from a bottle. I buy mostly Diamine ink, and, with one or two exceptions, purchase the 30ml sizes to try new colours and to ensure that I have ink that will be used up whilst fresh ( I have a box full of larger bottles of different inks which have gone off or dried out long before running out). Converters also need the nib immersed to fill them, and, depending on the pen and nib length, this cannot be done when the level is lowered in a 30ml bottle, or indeed a larger 80ml size. The solution, for me, is to use cheap plastic syringes to suck up ink and then inject it into the converter when it's out of the pen. I also find it a less inky process than having to clean up the cap threads, drops, spillages etc.
all went well for a minute or so then scratch, scratch, scratch, dry, not sure what to do but decided to try rinsing nib and things started happening again though in a dilluted lightblue way, let the pen rest for 45 minutes of Liverpool on tv then tried again and it was back to normal.
