kaluza: I don't like the second part: "A player who can't legally place a stone loses the game." If the player with fewer points is in a position where he would end up placing the last stone, he can force a win for himself by just continuing to play.

There may be another way to solve that problem:
If players don't agree on dead stones, they should play until no more dead stones are on the board. Passing is allowed but stones are counted as territory. (So passing gives you no advantage while your opponent fills up his own territory taking away dead stones.)