Hello Kevin, that was a big question for me too a few years back. After doing a bit of research up here and in a few other places I finally decided to go with KWM. I’m very happy I did. KWM seems to give a larger selection of bushings including and falling in between Bergeon sizes. There were other reasons I went with KWM but I don’t really remember what they were now.
Here are several links from this forum that cover the two systems.
Thank you for sharing your experience. I decided on KWM as well, mostly because of the type of connection of the reamers to the adapter I use with a drill press. Been working with clocks only six or so months. Improving slowly but surely!