With an opposed die system, with both sides using the same die, the probability of one die defeating the other, over time, is 50%. Your very first chart shows this--both sides of 0 are equal.
Let's say you're rolling an opposed d3. Excluding ties, here are the possible results:
wins:
2 1
3 1
3 2
losses:
1 2
1 3
2 3
See? you might as well just have one person flip a coin. You say as much at the bottom of page xci:
if the pools are the same size, your success chance is 50%
My point is, why use dice at all if you want a 50% chance of success?
