I have a couple of questions about the Orator feat and the Student of Philosophy trait. It seems like they're written differently in ways that might have different effects. I'm not sure if that's a deliberate choice or if I'm just overanalyzing everything.
You can use a Linguistics check in place of a Bluff check to tell a falsehood or conceal information, in place of a Diplomacy check to change the attitude of a creature, or in place of an Intimidate check to force a creature to cooperate. You must deliver your attempt in a language the target understands.
You can use your Intelligence modifier in place of your Charisma modifier on Diplomacy checks to persuade others and on Bluff checks to convince others that a lie is true. (This trait does not affect Diplomacy checks to gather information or Bluff checks to feint in combat).
Finally, the uses of Diplomacy, as described in the rules:
Gather Information: Using Diplomacy to gather information takes 1d4 hours of work, searching for rumors and informants.
Influence Attitude: Using Diplomacy to influence a creature’s attitude takes 1 minute of continuous interaction.
Make Request: Making a request of a creature takes 1 or more rounds of interaction, depending upon the complexity of the request.
Suggest Course of Action: at least 1 minute of continuous interaction.
Notice that we don't have "persuade others" on that list. The most natural reading to me seems to be that Gather Information is its own thing and the other three are all forms of persuasion.
Let's suppose that there is a witness to a crime that is hostile to our character. In response we want to persuade the witness to like us and then convince them to tell us what happened. If I have taken the Orator feat, then it looks like I can use Skill Focus(linguistics) to convince them to like me, but then I'm back on the Diplomacy skill to get them to testify. If I have Student of Philosophy then it seems like I should be able to use int for both as both are forms of persuasion.
How about some racial traits:
Human are often adept at subtle manipulation and putting even sworn foes at ease. Humans with this trait gain a +2 bonus on Diplomacy and Bluff checks. In addition, when they use Diplomacy to shift a creature's attitude, they can shift up to three steps up rather than just two. This racial trait replaces skilled.
Some half-orcs use half-orcs' brutish stereotypes to their advantage, causing others to underestimate their intelligence and scheming. Such half-orcs gain a +2 racial bonus on Bluff, Diplomacy, and Sense Motive checks. This bonus increases to +4 against other humanoids. They also receive a +2 racial bonus on Bluff checks to feign ignorance and Sense Motive checks to intercept secret messages, and this stacks with the above bonus. This racial trait replaces intimidating, orc ferocity, and weapon familiarity.
And regular traits:
You gain a +1 trait bonus on Diplomacy checks. This bonus increases to +2 when the Diplomacy check is made to influence those who are already friendly or helpful toward you.
The way I read it these would work with Student of Philosophy since it just changes the charisma modifier to an intelligence modifier. But they would not work with Orator since it is slotting in a linguistics check in place of a diplomacy check.
Does this all seem right? The Orator feat seems rather underwhelming.
You have the right idea about it. Orator changes what kind of check you make, so absolutely nothing that helps Diplomacy, Bluff, or Intimidate checks would help with the coveted actions, as you are making a Linguistics check instead.
Conversely, you are able to use your Linguistics skill ranks, and any Intelligence modifier, traits, feats, racials, class features, etcetera, that help Linguistics checks (without a restriction, such as only to decode messages).
Furthermore, if you had something that let you substitute other kinds of checks for Linguistics checks without any particular restriction, you could perform that secondary form of substitution. (Something such as Versatile Performance, for example, though as of this post's writing I am unaware of any effect that works for Linguistics)
