Here's a picture of Jim's Kabosu just taken yesterday.
It's put on some growth since I last saw it. (Which I find somewhat surprising since that was from the end of September to April)
Jim says it looks like it has the same level of hardiness as Yuzu and Sudachi. He says he was able to try one fruit from the tree. It got very big and orange, and developed a sweet taste.
Jim's Ichang Lemon (not Ichang papeda, to avoid confusion) tree is also doing surprisingly well, very big (over 6 feet), although Jim says it has never flowered or fruited.
(I suggested to him to give it a few more years, as some varieties can be much less precocious than others, and that it might fruit when it gets a little bit bigger or older)
Jim's Early St. Ann Satsuma (big tree) survived through the winter just fine, going unprotected for the first time, and Jim reckons it would have likely produced fruit this year. But we'll never know because Jim tore the tree out in early Spring. He got tired of protecting it, and says this winter was a relatively mild one for him, and it had become overgrown and was taking up too much space in the spot where it was. The last I saw of it, the tree was just a little over 4 feet wide, maybe 5 feet high, looked pretty old.
Jim also told me his huge Yuzu tree bush produced 50 pounds of fruit one year (either this winter, or the year before), and some guy who had a local brewery came and collected them because he was going to make fresh Yuzu flavored beer.
The very outer layer of the big Yuzu bush has yellow leaves, especially on the South-facing side, but the leaves inside the bush all look very green and healthy. Apparently the outer layer of the bush acted to provide insulation. The South-side is facing the street and that is where it is most exposed to winds.