Personally, I'd prefer 45-x over 50-2x. My reasoning is that the 2xpart is what really encourages hedging. With 45-x, getting the rightwinner still matters, but you take away the big incentive to pickscores near 50%.

My reasoning is that the 45-2xencourages hedging. People aren't afraid to lose the 2x itself, they'reafraid to lose more than the 5 points they already lost...
And furthermore, Exhibit A:
http://solarshadow-stats.tripod.com/oracle/oracle59.html

Y helo thar hedging. With 25-x. The more you penalize someone for picking the wrong winner, the less they want to take an additional risk...
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I've been officially pwned by yoblazer, best Guru of 'em all.