http://transitivegaming.blogspot.com/2008/04/social-combat-system-from-exalted.html

As far as the Social Combat system from Exalted, and porting it over to Scion, I think it’s a poor fit. That system uses temporary Willpower to track how well you’ve convinced, tricked, or intimidated someone. There’s a couple problems with that.

Willpower totals max at 10 in Scion, for both puny mortals and the most strong-willed Gods. So, it doesn’t really scale as you go up, and almost all PCs start at 70% of maximum. Social attributes, however, have a higher cap, and Epic socials expand almost geometrically (+46 automatic successes at the top level). Social characters will wrap the gods around their fingers with fairly minimal XP investment.

Rather than scaling up the willpower pools, the designers just made lots of knacks that restore spent willpower, especially in Demigod and God (but those knacks can be purchased by Hero-level characters). In fact, there’s several different knacks that refresh someone’s entire willpower pool for a single point of legend (and Gods have over 100 legend points). Two characters both armed with that power would render each other immune to ever being dissuaded.

I’d guess by Legend 5 or so it’ll break down almost completely. You’ll always succeed at persuading someone if you talk to them in private, but are incapable of affecting groups of 2 or more. That just doesn’t sound like fun.

A possible solution would be to create a new stat that works similar to willpower, and is the target of social combat, but which scales up like Epics and/or can’t be refreshed infinitely via knacks like some sort of M:TG combo deck. But that may be a lot of work to implement.

Personally I’ve gone both ways on it in the past, though perhaps never quite to the level of a social combat.

If the character needs to do something relating to a social skill there are times when it is best role played, and then I’ll simply judge their attempt and have NPCs react. The problem there of course being that some situations come up where the player may not be super suave, for example, but their character is supposed to be.

At the other end of the spectrum might be a straight dice roll, as you said “I make my argument” and roll, then go from there. This often feels wrong too, as most of the flavor of the interaction, the character cleverly duping a desk guard and so on, is lost in the reduction to a simple die roll. In physical combat there’s usually a wealth of detail about character locations, aspects of the environment that come into play, descriptions of attacks and their results, and more – shouldn’t some of this be made available to the social characters as well?

I have no experience with it, but the Scion system using stunt dice sounds like a good way to go. Have the player take his or her best shot at duping the guard through fast talk and charm, grant their performance some dice, then factor the character’s stats into the interaction as well. I like the opportunity to reward players for good role playing, but allow those who aren’t up to it to still have a shot when their character’s stats are there.