My hatch rates usually stay around 75%. I tried the egg carton method for two hatches in a row. Both of which had very low hatch rates. This hatch that just finished this morning, I went back to laying them on there side. My hatch rate went back up. 31 out of 38 hatched. That's proof enough for me not to use the egg carton method again.
I opened the eggs up that did not hatch using the egg carton method an all had the extra moisture in an around there mouths. I believe that if they were on there sides this moisture would have pored in to the air sack an away from there mouths. Looks to me like standing them on end makes drowning more likely.