I don't know if this will be of any value to your idea or your inquiry, but I submit my comments as just a series of observations.
There are multiple types of role-play. There is character type (class) role play, character persona role play, character position (in the group, what function does the character perform within the group) role play, character projection role play (character becomes a projection of the player himself), and character vocation (as opposed to class, what problem or problems does/do the character commonly solve or like to solve or what types of situations does he seek out to engage), etc. To name but a few I think.
I mention that merely to give you some avenues of pursuit. Whereas it is true that a player might cover all of these bases and more while engaged in role playing his or her character, they may also only apply themselves fundamentally in one, or perhaps a few of these categories of role play. I can play them all if necessary, but my least favorite is usually character persona role play (actual play acting) and my real favorite, generally speaking, is character vocational role play. Some people may appreciate one aspect more than another. I say that merely to give you something to consider in this regard. Whereas not all types of role play may be considered equal by any particular individual, it may be possible that more role playing is going on than you immediately suspect, just not all of it is, let us say, persona role playing. (The again some people may see persona role playing as speaking in character, whereas someone else may see it as "acting in character." As with actual human personality types, different people value different aspects of a given situation, setting, or challenge in different ways and will act accordingly in respect to their own nature, but not necessarily as someone of a different nature might expect them to react.)
I also favor active role play to mechanical systems.
My players often engage in debates, similar to Medieval debates, either against each other or against NPCs or monsters played by me. It's not really "social combat per se" but it is social competition affected by charisma (both personal on the part of the player, and character based, though intelligence, wisdom, and wit - which in this case might be considered mental dexterity, and I am a big fan of developing, sharpening, practicing, and employing wit - are also employed).
Anywho I have seen such debates and other such things, over time, assist players become better debaters and speakers in real life. I'm not against mechanical systems per se though, because a lot of mechanical techniques can be applied to real world situations, and therefore improve player's real world capabilities. These mechanical techniques, like other role playing techniques (analytical reasoning, deduction, observation, inquiry, etc) just don't happen to rely upon dice rolls in those role play situations in any given setting. But in cases like that mechanical techniques do lead to improvements in abilities, in both the player and the character.
(Or in other words, as an analogy to what I referred to above, there are different mechanical and technical methods, just as there are different types of role play. For instance learning good debating techniques is a mechanical exercise, but it relies upon the practice and repetition and mastering of real skills, not a randomized method of skill resolution. In a game you can of course rely entirely upon randomized methods of skill and problem resolution for role play, but there is no law saying you must reply upon such methods. Both learning new real skills, and simulating skill employment through die roll are potential methods of problem resolution in game through mechanical and technical methods, they just require different approaches and yield different results. As a little side I'm also not a particular fan of attributes like Intelligence, Wisdom, and Charisma being basically static, but I think such things can and should be improved by practice, exposure, and study, as well as "in the field experience." People improve such capabilities all of the time by these methods and more, just as athletes become stronger and faster and gain more endurance via athletic trading, and there is no reason I can think of why characters would not and would remain basically static in capability over long periods of time.)
Anyways it's just something to consider in developing your ideas.
In any case good luck to ya.
I'm actually personally a big fan of the Burning Wheel Duel of Wits system. I find that it actually encourages rather than hinders roleplaying. You plan your moves, then as they resolved roleplay out what your character is saying to actually fulfill his motivations. Plus, by having explicit mechanical "modes" of speaking it helps the other players pick up on some of the nuances you were going for.
That sounds interesting and of some potential to me because if I'm reading you right you are practicing the mechanical skills of tactical or maybe even strategic planning in relation to how you intend to execute your social skills and use of wit.
That would be a potentially useful ability to have in the real world as well, as long as the techniques used could be applied outside the game as well.
