Actually, I think it would be quite well suited for tabletop still life, Mark. It's not at all hard to use... you srew the macro lens onto your 80mm (and I'm pretty sure it has to be 80mm), then the framing thing attaches to an under plate type of thing that screws into the tri-pod hole at the bottom of the camera body. It has another screw in there for a tri-pod.
I got it at the time for the same reason. I didn't want to get another camera, but was interested in doing some closer shots with the Mamiya 7 and it seemed an economical way to go. Since then, I've added the RZ to my kit, and I would say I use the Mamiya 7 and RZ each equally, but really haven't found the need for the macro set up with the Mamiya 7 since getting the RZ.
All that said, it's a set up that is, I think, quite well suited to still life!