I've been hatching shipped eggs in my hovabator for 2 years, with greatly mixed success. I occasionally get a 60% hatch rate, but no better. I've also had total disasters. On my first hatch of last year I only got 4 chicks out of 38 eggs. It was heartbreaking, and a waste of money. Things that I have noticed that help: the shorter the shipping distance the better, arranging to pick up the box at the post office (my mailman was always rough with the package), don't turn the eggs for the first 5 days...that's right...5 days. I read a research article about it. I'll try to find the article.
 
I now try to avoid shipped eggs entirely if possible. I was pretty excited to find a Marans breeder 30 minutes away.