I've seen mixed reviews also. I cannot say I would have had different results if I didn't use the cartons, only that I hatched 100+ chicks and poults this year, and I was very happy with how it worked out and see no reason not to continue. (Also - I use a cabinet incubator that stands the eggs up during incubation, so I decided to keep mine standing up for hatching also.)
Basically what I do as well, though with a smaller bator


