Second for cartridges. Though I prefer bottled ink, the convenience of cartridges while traveling trumps this preference. I think it is a safer and more efficient way to travel with a handful of colors. For me, the only real alternative would be two or three
traveling inkpots, and so far I haven't been able to justify their cost (though they do tickle my "pen gadget" spot).
Plus, it's an excuse to try out new ink colors: "Well, I'm traveling next week, so I'd better find some cartridges. Oh look!
Private Reserve Sonic Blue! This is a good chance to try a new color. And as long as I'm making an order, let's see if there's any good deals on interesting pens . . . "
I also agree that flying with a FP in a carry-on shouldn't be a problem--modern pens are purportedly able to handle the comparatively minor pressure changes of a passenger jet. It was older, upressurized aircraft that spelled disaster for older FPs. My real concern is a random trigger-happy TSA agent deciding that my pen looks too imposing and must be seized. I know it's crazy, but it has happened and I'm not willing to risk an expensive FP on my ability to negotiate with federal bureaucracy. So any quality FPs get left at home or, if I can't live without one, in checked bags (where at least I can make an insurance claim if a screener or baggage handler gets sticky fingers). I'll bring a Lamy Vista or Pelikan Future on board if I anticipate writing during the flight.
No relation to the linked site, btw. Just one of several excellent places to buy ink--albeit with the super-ultra-cool
ink sample program.