Good Morning Spangle. I will follow up later with comments on New Hampshires. I'm heading with my grandson to look at some White Giants today. But here is a response to egg color being "recessive" and breeding for it.
The Marans Club of American has been working hard for years to get various "Marans" standardized and recognized by the APA. As I stated in previous posts to meet SOP you must meet body structure and color requirements[ but a judge isn't going to wait for the hen to lay and judge her egg color. So as I said previously if you are breeding for SOP then breed for body and color and not worry about egg color as a SOP factor.
Now what I meant about the recessive gene causing egg color is just that' it is not a dominate gene influencing a hen's performance. Since it is recessive it doesn't provide strong traits for future generations. You want strong dominate genes influencing a line of birds. There is nothing wrong with using a strong genetic line to improve weak recessive qualities but what I see happening too often is breeding for weak recessive qualities using "weak" birds to begin with. Remember you get what you start with not the other way around. So if you keep pushing egg color at the expense of all other qualities you create a genetic mess. My grandfather's life long friend Mr. Isaac (IK) Felch was perhaps the most stern breeder who ever lived, always insisted on an established line of birds be perfected before intention to make "improvement to the lineage should occur".
Because of this "weak" gene, a dark brown laying hen like the Marans will not always produce dark brown eggs but this shouldn't disqualify her from producing offspring (her offspring could produce the "holy grail" for Marans breeders by creating a dominate strain of dark egg layers who are also meet SOP). Also a hen that does lay "dark brown" eggs will tend to get lighter and lighter in color as she ages. This is also the nature of a recessive gene. So let's say a 3 year old Maran hen is now laying an egg far lighter than she laid when she was a pullet, do you stop hatching her eggs because they are lighter? She is perfect by SOP standards and every chick hatched from her for 2 years was SOP perfect. Since I use hens for up to 6 or 7 years for breeding purposes why would I stop using this hens eggs simply because they are lighter due to age?
This is what was happening to my young friend who I described earlier. She was discarding eggs because they were "lighter" than she thought was appropriate and keeping "dark" eggs that were from inferior birds. What she was heading for was a useless strain. Since then unfortunately I no longer get "free" eating eggs from her but this is okay because her breeding "eye" and experience are blooming and she has moved on to other fowl she enjoys looking now with a more experienced critical eye.
So I have not been saying it isn't a good idea to selectively breed for egg color; rather what I said was breed for body structure first second and third. If you have a successful line of birds that meets SOP for body and structure and plumage structure and color; then line selecting for egg color is also a good practice but for me it isn't a high priority for breeding generally; though I understand the allure within the Marans community. My allure for the Marans would be the fact that they tend to have lower incidence of salmonella egg infection. This is a trait that commercial poultry-me should be exploiting!
I point out that meeting all of that in breeding is a huge accomplishment for the seasoned, experienced breeder so I don't recommend pursuing such rigorous breeding techniques with little or no experience. I will preface that statement by saying the beginners often have amazing success even where the experienced breeder fails.
My overall point to "egg color" in the Marans thought process wasn't about Marans at all; rather it was about the idea of where a breeder's starting point to creating a successful line starts and that is with body structure. And as was pointed out by several folks here that is a tough place to start because it requires effort, time and a serious learning curve to achieve.
So pickup your birds and "feel" the structure under all those feathers as feathers can often hide a multitude of sin. When you go to shows or have a chance to meet with an experienced breed ask them what they are looking for and boldly ask them to show you on the bird. 99 out of 100 senior breeders will be happy to have a show and tell session with their stock. This is the best way to a solid line of experience. But again when a breeder only wants to talk about how perfect their birds color is or how perfect their topknot is then ask the question "what about their body structure?" If they balk at the question or stare blankly then be polite and smile and thank them for their time but don't take to the bank what you've learned as it isn't sufficient.
Remember learning 63% of something first is better than learning 37% first isn't it?