Will different sizes of BioPace rings produce differing amounts of variation in chain tension?

I recently came upon two BioPace rings: one around 40 teeth and the other around 50. My intuition tells me that using the 40 tooth ring with a smaller rear cog would result in less variation in chain tension than using the 50 ring with a larger rear cog. If I'm right, would the variation be enough to warrant choosing the smaller BioPace ring?

For that matter, theoretically, does a large BioPace ring produce a larger performance gain relative to a small BioPace ring?

What would you choose: (large BioPace ring and large cog) or (small BioPace ring and small cog)?