Just a side note, it's worth bearing in mind that you get penalties to perception for distance. No matter how good Vershab's eyes are, he's not going to notice from 20 feet away what Calathon will notice up close (granted, a -2 penalty isn't likely to be game-breaking, but it's just another layer of complications for you to keep track of ^_^).

Ironically, it's about the only thing in the entire game that tends to work in rogues favors.... so naturally it is ignored, basically always.