Brian, I'm coming late to this thread but I'm happy to recommend the Ebony "S" cameras. Although I use it exclusively for roll film I went for the 45S, for the following reasons:
1. More bellows freedom than the 23S. I wanted to use the 55/4.5 Apo-Grandagon lens and the 23S will not allow full use of the image circle because with rise, the top of the rear element of the lens hits the underside of the box which forms the rear standard. This box is bigger on the 45S, so allowing full rise with this lens.
2. Ability to see outside the 6x9 frame on the ground glass. I find this to be a great help when framing a picture.
3. Selling it on might be easier (I have no plans to do so!)

Of course the 23S is a bit smaller and lighter, and users of the Ebony 2x3 cameras really like the hinged back, which does away with the need to remove the focusing frame and find somewhere safe to put it (often in a hurry). However the Horseman roll film backs fit like a glove on the Ebony 5x4 cameras, and they are not that much bigger or heavier than the 6x9 backs.