Thanks for the post. I think it would be worth having a section for hybrid photos, but regardless of how many photos this accumulates I think that sexing most hybrid chicks (autosexing combos aside!) is always going to be an uphill struggle! This is because the combination of genes from different breeds can have synergistic effects that won't always be possible to predict. This will particularly be the case for hybrids in the second generation and beyond. A first gen (F1) hybrid between two pure breeds should be relatively consistent genetically, because each of the parent breeds have relatively homogenous genetic makeups (if this isn't the case for the breed then it is unlikely to breed 'true'). However, the genetic input into the F2 generation from hybrid parents will be much less consistent, with the result that genotypes will be more variable, and the resulting phenotypes (the characteristics such as feather growth, colour, head-gear etc. that have a largely genetic basis) less predictable. Add to this the fact that many commercial hybrid cocks show minimal development of secondary sexual characteristics, and owners of mutts really are up against it when it comes to sexing their chicks.
That said, the easiest to sex of the 12 birds I've raised from chick, apart from our Welsummer and Cream Legbar, has been a hybrid. Snowball, our Buff Orp/White Leghorn cross, already had a prominent red comb at 3 weeks, and was chest-bumping birds twice his age even earlier. Now 7 weeks old, he gave his first strangled crow a few days ago (from a different room I thought something had fallen on him, he sounded so distressed). Particularly for hybrids of known parentage, I think photo illustrating when they can and can't be sexed would potentially be very useful. But I probably have to think of a cleverer way of organising them than I have set up for the pure breeds.
Thanks again and let me know when the gender of the chicks you are photographing becomes clear!