I'm sorry, I have no room to speak.
Sounds like you will have an awesome grand adventure with whatever birds came your way!
I like the Marans a lot. But everyone who comes over likes the Speckled Sussex. They did dress easier, but we haven't sampled the meat yet. As far as breeding to the standard goes, they are easier than the Marans for sure. And should lay an extra egg or so per week once mature. Though their eggs may be a tad smaller than my Marans eggs which usually come in at extra large to jumbo but definitely only 3 per week.
That being said... I'm not stuck on dual purpose. I love my white faced black Spanish. They aren't super meaty but they are super fun to have on pasture and lay slightly smaller but still prolifically. We process the extra boys and that includes Silkies, Sussex, Marans!
I will admit the Wyandottes we processed were quite tasty. They didn't lay well enough, early enough for me and are a bit too broody. Just not my personal choice but maybe still a really good choice.
And lets NOT forget the Naked Neck Turken!
Are you kidding me you've gone and scratched that itch was semi subdued!

Can you say chicken math?!
I didn't get to eat any of the Turken and sold them off before they started laying. But while they were here they were great and confident, friendly, INTERESTING birds. My processor absolutely thought they were fantastic! Sooo... maybe a consideration.
I truly recommend going with what you might love. Something you enjoy the look of and use it to feed your family. Things are never the same in reality as they are on paper.
My Marans are also broody and lay into their 4th year (my limit). I mean it's a good thing if you want to be semi sustainable. But it isn't always convenient. My Sussex haven't haven't been laying long enough to display their broodiness. I suspect they will be just as broody as many other breeds I have tried.