@Troodonte - i think the reward for stopping someone solo-ing should be considered.
If everyone is just playing to win then once they can no longer win they're more likely give up. If some people are willing to accept a draw then a player with only one supply center left has something to contribute to that draw, and is hence more likely to survive and grow... (perhaps even going on to win if he's lucky)
1 point for a draw and 5-7

for a solo seems about fair.
Any draw, though 7 palyer draws might give a player that 1 extra point to bring them from 7 -> 8

and thus be as valuable as a win if that will make the difference...
hmm...