The approach I'm advocating here is to check all the other options before even thinking about attacking the nib with any form of abrasive. A loupe is a better investment than a nib smoothing kit, in my experience.
Hey everyone! Before you start Max Factoring your nibs to death, maybe take a breath and either Google or go to a local art supply store and look for some "Flex-i-Grit" Sanding Film. Made by K&S it's great micro sanding material. Comes in sheets. Each package has 1 sheet each of Chrome oxide .5 micron; Cerium Oxide 1.5 micron; Silicon Carbide 8 micron; Silicon Carbide 23 micron; Aluminum oxide 23 micron. This is the ONLY thing I would recommend you put to your nibs, ESPECIALLY those gold nibs you paid so much for. REALLY! This stuff has been a lifesaver for me because it allows you to start at the very lowest/safest roughness and then smooth it out gradually down to the smoothest polishing .5 micron texture.
As far as the nail buffers are concerned, the gray part of the nail buffers is 12000 grit (2 micron) micro-mesh. The gray part is the only bit anyone has suggested that anyone use on a pen. Used with due care, it isn't going to Max Factor any nib to death. The other parts will, undoubtedly.
Of course, even the .5 micron chrome oxide films will wear away the tipping of a nib, given sufficient determination.
While I'm at it, the TWSBI facebook site has some good pictures of nib adjustments. Well worth checking, even if you aren't a TWSBI owner.
Edited by troglokev, 15 September 2011 - 11:39.