I have grown a few different limbertwigs long enough to have some experience with them. Black LT is in the upper echelon of all apples I've ever seen. It has incredible DR and just makes crop after crop, year after year. I had two good trees that had to be moved with a backhoe due to the new road. That set them back but they are recovering and loaded with blooms this year.
My Myer's Royal and Caney Fork have given small crops so far, but both are loaded with blooms and have set lots of fruit this year. Both have good levels of DR. I'm anxious to see what the year brings with them.
Brushy Mountain is one of those apples that will show lots of fireblight but seems to grow so vigorously that it overcomes it. I almost top worked mine once but glad I waited. It had a massive crop of apples last year. This year it has only a few blooms, so I guess it may be catching its breath after that bumper crop. I would recommend not letting this cultivar fruit at a really young age and get some size on it first due to it getting shoot blight via the flowers.
My Old Fashioned LT is young and just started blooming last year. It has a few this year. I have a good feeling about this one based on what I've seen so far. It reminds me of Black LT. So far I see nothing affecting it at all. It just needs some time.