Hiding in Plain Sight with the way so many quests are designed will ultimately do very little. Besides, you have Faster Sneaking as a rogue, which is generally far more valuable when doing stealth-based things.

Also, Hiding in Plain Sight isn't a rogue ability. Its something obtained by rangers, shadowdancers, and assassins. If anything, you should request that Assassin III adds Hiding in Plain Sight.