If there's a scoreboard system, I suggest using the scoring system I've seen before: each game is worth 10?number_of_players points. If one player wins by controlling the objective number of SCs, he gets all the points. If multiple players win by stalemate or draw, each player gets game_point_worth?number_SCs_controlled?total_map_SCs points, rounded to the nearest integer.
As for testing interest, simply running another game, and then another game after that one, and so on, won't be that representative ? I suspect all the games will generally be played by the same users (i.e., us). Perhaps we could run two games side-by-side and see if there's enough interest for players to fill up both games, with the (obvious) restriction that any user may only participate in one game at a time.