jbombelli made some good points, a sheath that hugs the blade tightly will probably cause more scratching on the blade, however any kydex sheath will eventually encourage wear or scratching. I say encourage because it's actually any possible debris that might get between the blade and the sheath wall, and it doesn't take much at all. It doesn't show so much on coated blades but on shiny blades like the LE it's almost impossible to avoid some scratching unless you keep both the blade and the sheath super clean. I've come to except a few scratches on a shiny blade it's practically unavoidable. About the only way to avoid scratches is to use a soft leather or cloth lined sheath. Even then there's no absolute guarantees, debris can still get to them too in time without proper care, it's just not quite as likely.
On other point to make satin finishes seem to be the most prone because debris caught between the blade and sheath wall are forced to travel irregularly across the surface, so extra care must be taken. I usually try to discourage the use of kydex on an LE unless my impression is that the blade will be a user an then it really doesn't matter anyway.
Last edited by Rainwalker; 01/14/09 12:23 AM.