This is interesting. It sounds similar to their "Orylag Rex" or Rex du Poitu rabbits that are essentially a strain of large and very wonderful rex-coated rabbits, but the husbandry techniques are so exact and strict that it completely changes the flavor of the meat. The techniques are surprisingly similar to what you describe for the Bresse, including castrating the males, very specific and high quality grain and alfalfa diets, and generally just babying the animals.
The same rabbits raised in other conditions taste the same as any other rabbit, but the uniqueness of the strain remains. (In large part because of the fur, many generations of selective breeding for size and coat density makes it incomparable to anything else.) Like the Bresse, they are also very protective of these rabbits, I believe it is nearly impossible to get them unless you are a licensed farm that has been rigorously trained in the husbandry practices. Because of this, they get far more for their rabbits than any other rabbit enterprise in the world, and have maintained impeccable reputation and a marketing campaign to support it.
We could learn a lot from the French about how to increase the value of our animals through good husbandry and smart marketing.
The French also have a rich appreciation for varieties of animals that grow slowly on high quality diets. They would positively sneer at our 12 week finish on either our rabbits or chickens, from what I have been told.
