I'm a huge fan of my dip nibs - I use them almost exclusively for my line art (plug: I drew about 98% of my graphic novel with my #102 crow). Problem is - I'm about to hit the road for the better part of a year and I'm trying to figure out a decent alternative to dragging around and using a leaky bottle of ink, sponges, etc while riding trains in China and Central Asia. And for those more sedentary times, I'm the kind of person who "deploys" - I array all my stuff in a way that's really irritating to move. Usually that means leaving a sketchbook and pencils, etc around, but with ink, it means the nibs, paper towels, sponges, ink well, scratch paper, water, etc. Not very mobile.
I like the ability to produce both strong, fine lines and broad strokes and the rigidity of the metal. I started fiddling with a brush pen which, although beautiful, produces really thick, broad strokes or finicky thin lines because the brush tip is wussy compared to a nib (duh). My Copics have no line variance, obviously.
The only other compact and travel friendly thing I can think of trying next is a fountain pen, but something tells me that won't work out as I'd like either - any suggestions?