In a previous post at https://forum.grin.mw/t/what-to-mine-choosing-between-cuckatoo31-and-cuckaroo29 I concluded that mining C31 is preferred when
(GPS31 * F31 / 42) * weight(31) > (GPS29 * F29 / 42) * ar_scale.
where GPS31/GPS29 is your miner’s graph-rate on Cuckatoo31/Cuckaroo29 and F31/F29 its fidelity.
For cuckarood29, due to doubling the expected solutions per graph, this criterion becomes
(GPS31 * F31 / 42) * weight(31) > (GPS29 * F29 / 21) * ar_scale,
In other words, C31 is preferred when
ar_scale < (weight(31) / 2) * (GPS31 * F31) / (GPS29 * F29).