I raise Flemish giants and New Zealand crosses for meat. There is a lot out there about not using Flemish Giants for meat purposes, but a lot of people cross them with New Zealands for meat. I've heard breeders more experienced than myself say they prefer them for meat purposes. You absolutely can use Flemish for meat. They still have a lot of meat. There is way too much information about how they have to grow their bones when young and therefore don't have as much meat, but I am beginning to find that it is just repeated information. I would love to find an actual breeder that can place the two side-by-side at butchering time and show me the results.
Like I said, though, there are many people who prefer a Flemish/ nz cross for meat. I am a newbie, but I have butchered mine and find them to produce good meat.
After I butchered my last 3, they weighed 2 1/2 pounds without the backbone. I have cut the loins off of the backbone then weighed the results with front and back legs. I have read a lot of people talking about how their New Zealand's butcher out to be 2 1/2, but that is including the backbone. So, I think mine are producing the same amount of meat than straight New Zealand's, which are the most prominent meat rabbit breed. And those weights are at around 12 weeks. I have butchered at 14 weeks and get good results as well.
As a side note, I don't think I will take the loins off of the backbone the next time. I need new butchering tools/ knives, though, to make a prettier cut. I'm hoping to get a pressure cooker next month and can't wait to experiment with that cooking rabbit.