Hmmm...I think I have a couple of issues, so what the heck...I might as well get 'em off my chest. :thumbsup:

If the seed-sexing theory is right, this implies that sex is pre-determined.
And if you can stress a female seedling into being male, why don't more newbies suffer from 'over-abundance of males' syndrome'? But, I'm not all that certain the seed-sexing thing is on track anyway.
Granted, I have not tried the technique, but am of the opinion it's likely not reliable. Mainly because during formation, seeds can get squeezed together, pulled, pushed, tugged-on...which can and will distort the attachment point for each seed. I've had seeds long and thin, round and plump, round with a dent or two, almost 'cresent moon' shaped...all from the same strains. Any distortion of the shell does impact the attachment point structure.

And having femmed seeds a few times, (and I still do on occasion) I have never stressed a female into being a male. I've stressed a female to provide pollen sacks, (become hermaphrodite on command) and after harvest I've re-vegged a forced hermaphrodite back into 'normal' female re-growth, but never has stress switched a cannabis plant's sex, in my garden. Since I doubt you change the (sex determing) chromosomes through stress, a sudden and wholesale sex change is unlikely, and nobody has added chemicals to the discussion.

Beware of strains with past or present 'purple' genetics when using the color-coded seedling-sexing, as the normal coloring of the seedling might skew results.
I'm guessing that cooler growroom enviornments might skew coloring, too.

As I previously stated, I haven't tried the seed-sexing. But it just didn't sound right when I first heard it a few years back, and I still have doubts.