Am seriously considering having a mount added to my '91 Kona Explosif as I am planning on having the cable housing stops moved to the top-tube. Figure if it is gonna be at the frame shop, I may as well add the rear disc mount while it is there.
I have an Ibis Bow Ti. Mad bike, totally unique but flawed. The biggest flaw was the seat stays were so long that they offered no resistance against flex when the rear cantilevers were used. The rear brakes were basically useless on these bikes. Disc brakes were a godsend. I had Steve Potts add the rear disc mount, he and Jon Castellano worked together to restomod it for me and turn it into a real fun bike to ride, and stop.