But anyway in Baldurs Gate it is class speciality, not everyone can do it and its compensates the otherwise low damage output of those rogue classes?
And in D:OS2 you have to spend one entire Talent point to take Guerilla. I don't see why Guerilla can't be a game-changer like Lonewolf or Savage Sortilege is. I believe the consensus is that Lonewolf is plain broken.
EDIT: Now that I think about it, buffing stealth in general might make stealth + Lonewolf too broken, but hey Lonewolf is already broken anyway, right?