You don't really need the size of 4x5 unless you print big all the time, i.e. larger than 16x20. If you use nothing but fast films, there would probably be an advantage too. There is a lot to be said for the convenience and cost factor of roll film (not to mention the availability of different products to fill your backs with). There are 6x9 options out there with plenty of movement for decent prices. I would look into the Horseman medium format technical cameras with their matching lenses.