I have a Xerox lens, but I haven't used it yet. I'm waiting on a back for the Speed Graphic and then I'll take a few frames.
Basically, it's heavy and it only goes down to f/16. It *looks* like it would cover 4x5, but I'm not quite sure yet. I won't be until I take photos with it.
I would probably say no, though, it isn't worth it. Most won't fit in a shutter and it'll be a novelty thing at best.