Ditto to all the positive kydex attributes that Rosco already mentioned. Also, and I may be a bit biased in this,(we manufacture kydex holsters), I like the little "snick" noise that kydex holsters make.
tuc22, the way our holsters are designed, I really can't see a way that the screws will just fall out. We include tension screws in our holster designs because not everyone likes the same amount of drawing tension in their holster. An allen wrench is included with every holster we sell to allow the user to adjust tension to their personal preference.