1) I am sure GClef, whose beautiful writing samples enhance many posts here on FPN, gave you some good info about flex nibs in his first post, but on my computer, for some reason, the post is blank (shows a broken picture link,) so I will give you my inexperienced impressions of what a flex nib is for. I don't yet have a pen with a flex nib but my understanding is that it is for the fun of line variation, plus the nib should slow down the speed of your writing so that you can actually end up improving how you write. Guess I will find out if I get brave enough to try one of the flex nibs for my dip pens!
2) I shouldn't think an eyedropper pen would be ideal for testing ink samples - a waste of capacity, for one thing, as sample vials really don't contain all that much ink and won't even begin to fill an eyedropper - plus eyedroppers often mean some extra cleaning. I would use an eyedropper for a nice big fill of an ink I already enjoyed and "trusted" to write well with my writing style, pen and paper. I usually buy a sample with a specific pen in mind and test it in that pen; otherwise, testing with an easily cleaned dip pen or cartridge fill pen makes more sense to me than using an eyedropper.
ETA: lol - GClef replaced his photo so now I can see his post, and it looks as if your questions have already been answered - it took me too long to post my response. Hope the repetition helps!
Edited by OakIris, 15 October 2013 - 16:43.