All I can say is that personally, I would only put the Bromberg Pre with the RAD-S pickups, and no others. The RAD-S's might work passive or with other pres, but the RAD-Singles and the Bromberg Pre are made for each other.
The RAD-H's do NOT work with the Bromberg, but sound fantastic w/the Icon Pre, IME. From experience I can tell you that as great as the pre sound w/RAD-S pickups, it is inversely awful with the RAD-H. I would be concerned that the Bromberg Pre would not sound right with his current pickups. That pre is designed for the Radiused Singles.
I'd try different pickups before I'd swap the pre...