I mostly did demogames ranging from 500-750 points per side, so that both newbies are able to keep track of their units and it worked out great.
But for the last conventions we actually took a painted up Gunfight at Red Oak box and splitted both posses.
After most games people asked me what's inside the two player starter box and i was able to point directly onto the models and the rules material they just played with.
Usually they were pretty intrigued by the low price point of the box because they could already relate to all the stuff which comes with it, which resulted often enough that after two to three convention days, the Red Oak box was all sold out.