Based on my vast experiance hatching ( just 1 hatch, 7 eggs ) I had mine in cartons and noticed a few things.
Pipping and zipping went very well, all were 1/3 or so down from the top of the egg.
The chicks had a bit of a bad time getting the " lids" off of their heads, the lids just kept falling back down on them.
The chicks toes were at or near the zip line once the lids were out of the way. This meant that they had to completly lift themselfs up to clear the edge of the egg.( Imagine your butt in a barrel and trying to get out on your own ) All of my hatch had problems doing this and I think they spent way more energy than they would have had the eggs been on their sides. I lost one chick after hatch and I think it was plain ole exhaustion that did it.
They spend a lot more time with their butts sitting in the leftover goo ( 2/3rds of an egg makes a good cup ) their repeated attempts to clear the egg let air get to the goo and as it partialy dried gave a couple of them problems, even at 75% humidity.
All of my chicks made a bee line for the flat floor of the incubator, and stayed there until they started exploring.
I have 20 eggs setting in cartons now, 1 week to go. I will be letting them hatch on their sides on the incubator floor because I think the extra energy they use getting out of an upright egg could well be used elsewhere.