Sure, there are some converters that are notably, notoriously small (Namiki Vanishing Point converters are infamous for this), but in those cases it's simple to use carts instead. (In the Namiki case, the carts last weeks and weeks.)
edit: lol, if I had reloaded the page before commenting, I would have seen all of these people saying the same thing!
Every time fountain pens come up on HN I'm amazed how active the discussion gets.
* Fountain pens * Mechanical watches * Cars with clutches
E.g.,
https://duckduckgo.com/?t=ffab&q=fountain+pen+piston+convert...
Just to expand on the time before refills. Most converters are under 1 ml. Having, say, 3-4 ml in your pen means you fill it a lot less frequently.
The thing keeping me away from eyedropping my pen is the inevitable burps.
I don't need a project, and I'm not super interested in locking a pen into a single mode of operation. The beauty of most pens is that you can go with carts OR with a converter, depending on mood. (Obviously some, like Pelikans and TWSBI, are bottle-fill only, but you know that going in.)
For a lot of pens, there is no "locking". You just remove the cartridge/converter, and add silicone, and you're good to go. You can always revert back.
I ran carts only in my Vanishing Point(s) for years, but largely because it was easier for travel and I found the ink color and consistency very pleasant.
Once I stopped traveling so much I started using more bottled ink, which is fun, but then you get to a point where you have a mental matrix about which inks work best with which paper in which nibs…
