I really like the look of Verwerk hens, but have never had them myself. I recently bought 24 eggs from Ireland, due to hatch on Friday. The woman I bought them from was very helpful and advised me to candle them before setting the eggs.
This was interesting. 8 had airsacs that had been detached by the post and floated around inside the shell. She said these would not hatch, and true enough none developed past a few days. I was also able to see the size of the airsac in the others; the airasacs were expanded loads, in a really uneven way. Leaving them to stand for a day or so does reduce the size of the airsac. I drew a pencil line around the airsac, will be interesting to see if the more distended, the less likely to hatch.
I read since that by setting them vertically in the incubator, wide end up, the airsac is collected and hatch rates of posted eggs can be improved.
I look forward to having breeding pens of my own and better hatch rates!