I have a level 5 Ranger (Galvanic Saboteur) with Constructs (+4) and Humans (+2) as favored enemies. By my reading of the feat, if I were to pick it up, I would now have a +8 on attack and damage vs robots, yes? +4 for being constructs from FE, and +4 being Robot's Bane, which uses my bonus from FE (Construct) in place of the bonus normally granted (+1 at this level). The line at the end of the special section implies that only the bonus to AC and saves should be replace with FE, but it doesn't actually disallow the attack and damage bonus. I know it's too good to be true, so what am I missing?
I think it's meant to be just the ac and saves. The wording is a bit broken as is, though. It says you may use your Favored Enemy bonus in place of the bonus (singular) granted by this feat. Which would mean the feat does nothing for you, RAW?
you can use your favored enemy bonus toward constructs in place of the bonus granted by this feat if it's larger..