Wow, so many questions: good thing I love to talk pork. Bottom Line to your question, if you're choosing between Kurobota and berkshire, I'd just buy Berkshire. But as for me and my house, we choose Tamworth!
Yes, you have your breeds classified correctly, hamps, yorks, durocs are commodity breeds raised in CAFOs (confined animals farming operations) and they do well in confinement. Heritage breeds prefer the outdoors: they need their sunshine, grass and dirt like God intended.
Full disclosure, I like Tamworth pork better - especially because I breed and sell these animals. A Tamworth is an heritage breed, but a breed that does not throw on inordinate amounts of fat. If you grow them out to around 300 pounds, carcasses have great marbling. The Tamworth belly is very ample, and if you check my post in the bacon and ham forum, you will see some pics of one of the larger bellies I cured and some of the hams. What really cinches it for me with the tams is the fat. In short, it is buttery. It is not a glob of sticky substance in your mouth that you want to spit out. It is beautiful and unbelievably tasty. A couple of weeks ago, I finished home-curing two Large hogs worth of bacon and ham. Here's a shot. I had to cut off lots of the ends as the bellies were too wide to fit on my 12-inch slicer, (which will take an 11-inch-long slice). Incidentally, these bacon slices could have been up to an inch wider in some places, but me and my dull knife trying to skin two hogs in the front yard in the freezing cold cut too much of the fat (and some of the meat) off the belly.
Yesterday, I received back a small acorn-fed Tamworth pig (225 pounds) from the processer and pan-fried some 1 inch thick chops with just some salt and pepper. -- Nothing finer!!!! Here is a pic of some of the chops we received back (frozen). I did get one of them overcooked and the center was dry - but Tamworth meat will dry out if you overcook it. Most store bought pork is dry despite of finishing temp.
Now for the berks. Berk is a different kind of pork. According to the heritage pork website, The Berkshire hog breed dates back to the 1600’s, rumored to have been first discovered by Sir Oliver Cromwell who prized Berkshire hogs for their superior meat quality. During this time, the Berkshire was described as a reddish or sandy colored pig. Approximately 320 years ago, East Asian black pigs were imported to England where they were crossed with the Berkshire producing the black coat and 6 distinct spots that we see today. The British Royal family has been dedicated to breeding Berkshire hogs and are known to have herds at their Windsor Castle estate.
Berkshire Pork is more gamy and has a more beefy texture and taste. It is cherished by chefs and is far more easy to get than Tamworth. In fact, the USDA has told me that our farm had the only US Certified Tamworth Label known to them. Laquercia Cured Meats sells Tamworth pork online that (according to their website) is 75 percent Tamworth/25 percent Duroc. One of their prize acorn-fed Tamworth (75 percent) 14-pound dry-cured ham goes for 900 dollars - Really!!!!.
Incidentally, Here is a pic of a Plant cured (not quite as good as dry cured) and smoked 14 pound ham in my freezer right now. The hogs had acorns the last four months of their life just like the high-dollar ones. I had the other ham sliced and here are some pics of the frozen ham and the slices. I can't wait to taste them, I'm sure they'll be great!! And yes, the ham is already sold.
Now, for the distinction between your Kurobuta pork and Ameican Berkshire. Kurobota pork comes from Japan and is a descendant of the original berks sent to Okinawa by the King of England centuries ago. Without doing a comparative taste test, I would say that most if any difference the Kurobuta and the American Berkshire meat is most likely the result of animal environment, feeding and butcher size. So, if I wanted Kurobuta pork, I'd just by Berkshire pork instead. But as for me and my house, we will enjoy Tams.