I had and still have a few Buttercups, they are my favorites. They lay small white eggs and are great pickled and for cooking, baking. I have used them as meat birds on the foot and even at 8 months old we find them still somewhat tender and prefer their meat to EE's or Turkens and they have better flavor than store bought, including organic Cornish crosses. Given time, my girls are about as big as my EE's or plan on 2 birds instead of one. They will hussel most of their own food if allowed yard/field time so are economical eaters.
If you are in south east Texas, I'll gladly trade you some of my Turkens for your Buttercups. We want to breed the Buttercups and I haven't been able to get more of them. I have a few hens but no Roo. Next Year......
Also, they are Sicilian Buttercups, being Mediterranean they were developed mostly for their laying ability. A hen should weigh 5 lbs, a young pullet 4lbs and they do mature early. America chose the gold version and thus saved it, but now they are rare. In Italy and elsewhere the darker brown version exists. Yes, I like American Buttercups.