I\'m too new at this myself to offer much more than an observation, but my blacks are all very closely related, as are the lavenders, and I\'ve had low hatch rates and high mortality, and the birds that made it are unthrifty and slow to mature. My buffs are from different, but related, flocks. I\'ve had nearly 100% fertility, think I had maybe 3 clear eggs all year, very high hatch rates, low mortality, and they\'re tough as nails. My w/bws, from unrelated flocks, fell in the middle. Again, just an observation from a small number of birds, so may have no meaning what-so-ever, but I was surprised at the buffs, since low fertility/hatch rate seem to be a problem in that variety.
I know what you mean about shooting in the dark. This past year I took a shotgun approach - hatch as many birds as possible and hope something stands out. A couple of offspring have, so going into this season with a more conservative (and hopefully less expensive) approach.