They are definitely better layers. The Orpingtons x Marans are excellent layers as well. I did a cross of lavender orp male x black marans female and the offspring hens lay pretty much every day, a #4-5 (on the Marans chart) extra large egg.
This is kinda hard to tell from the pic but the egg on the left is a Olive egg. The one on the far right is Flopsy's egg (she has a straight floppy comb but is Ameraucana x Marans). It is brown in some light but has a greenish cast. I kinda like it. The other straight combed OE girls seem to lay this way too whether crossed back to Marans twice or just once.
Another OE ...just for fun LOL