This requires some kind of interaction with the auth that is both direct and (preferably anonymous). How will this be handled? Will there be some kind of submission form that requires a post reference? Because someone going beyond the usual to say 'this person was a great help" is definitely beyond the norm.
How often do any of you fill out those "How did we do?" surveys at stores and restaurants that even reward doing so? Even when the person serving/helping you was awesome? This is the sort of thing that makes me feel a bit guilty later but not enough to make me do it. I feel like this method of earning/achieving ace will be under utilized.
If possible, could you make it a part of the reputation feature? Like when you go to +1 a post, could there be 2 options- I like this post or this post was helpful? Or even a third that proclaims the post as both? Can I also recommend some sort of tracking feature that shows an alert when such a thing happens for auth review, just as reports do? Or disable such things from counting in places like the wasteland? oh boy, all the details and methods of handing it... Glad I'm not auth and have to deal with this stuff seriously. Giving me more work 'n shit.