I have several Dominiques I hatched out with a large number of chicks of other breeds (53 chicks total). In that hatch, I also had Light Brahmas, Speckled Sussex, and Barnevlders. Currently the are 14 weeks old. Of the four breeds, the Dominiques appear to be the largest. I haven't really examined them to see if it's their feathering that is making them look bigger or if they are meatier than the others. I got the Dominques as bonus eggs when I bought the Barnies, I didn't even know I was getting them until I opened the box, so I had no intentions of using them as meet birds. As I've noticed their quicker growth compared to the others, I was starting to consider them as a possible meat bird. But like I said, it could be their feathers that are making them look bigger. I will have a few extra roos, and I am going to butcher them in 6 weeks (my meaties will be ready then) and see how they dress out. If they dress out decent, I may use them as meat birds in the future.
I'm pretty sure the early pioneers of America had Dominiques w/ them as they crossed the Mississippi and headed West. They lay a decent amount of eggs and they used them for meat when they needed it. It will be intersting to see how big they get by 20 weeks. I'd also be interested to hear from people who have raised and butchered them.