All I can say is that I do not drive a commercial breeding facility but that I have produced a few hundred grandis in the last 22 years.
Sexing of subadults as you all know, is a challenge, since a significant number of males does develop predicitve pore sizes later than the averadge and thus are often misidentified as females.
After a few years, I had the impression that other dimorphisms are more reliable than pore size if the animal is younger than 6-9 months.
From the feedback I got, I´d say I am like 85% right if the animals are older than 2-3 months.
So for my strain of grandis this works pretty well. But as grandis blodlines may diffe rin many an aspect, I am curious to see how it works across the atlantic ocean

Ci@o

Ingo