Just a tip for people wondering how to keep their bearing clean — get a can of compressed air. I’ve recently found this to be the best way to get them as clean as possible. The button on the SB’s unscrews by hand, just like a two halves of a yoyo. Flush with propyl or soap and water, then blow out the bearing and the insides of each half of the button with air, and reassemble. On the customs, if you don’t want to take the button apart (it’s not as easy), put it under running water and spin it – the water will get in there. Spin dry, then take the compressed air and blow it into the gap between the frame and the button.
Re: New button: Design evolution, plus in-house machining capabilities vs those of a pro machine shop. Eventually the custom buttons will be made the same. Also I initially opted for the bolt through design on the customs so I wouldn’t have to worry about material choice — some materials are either too difficult to tap, or too soft to hold the threads.