Numerous threads with literally hundreds of posts have been put up re. thumbs for BX 22, 23, 24, 25 and other BXs that have Woods BH6000 bh. BroTek was long favored over Wallenstein generation I, II, and III due to design flaws: collapsing jaws and slippage which broke hydraulic cylinders. Wallenstein generation IV has not had any reports of problems posted that I know of, though I may have missed it. BroTek has never had any problems reported here.
Do a search for "BX" together with "thumb" in the two Kubota forums with no date restrictions and you will find enough reading to keep you up all night.