I think you've gotten an answer that makes sense. Its very possible that porous eggs are more delicate for shipping. There are breeds that are more difficult to hatch with shipped eggs; theres no reason to think that porous eggs wouldnt be the same way. Obviously, since people have had good luck with porous shipped eggs, the issue IS shipping. Either the bad weather, rough handling, whatever, the porous eggs apparently dont ship as well. Ive gotten different breeds of eggs in the same box, with one breed developing much better than the other. It didnt mean they were bad eggs; they were just more delicate.