For myself, my Horseman kit has turned into a kind of a niche system--especially since the Sinar Norma in 5x7 and now 8x10 came along. (Fits a lot better in the top lid of my backpack, though.
) Otherwise, I guess my question is whether you're looking for an "all around" 4x5 camera, in which case I'd say the Chamonix's longer bellows probably makes it more versatile. Of course, if you're just looking for something to handle the format, you could pick up a 4x5 format change kit for your Sinar--or just a 5x7 to 4x5 reducing back if you need the bellows length.