I would definitely keep the zz! I find too many things I need to use it for. I usually keep 6 machines set up. My 27 treadle for most anything, my serger, my Janome 10001, an old Singer 4662 on a quilting frame, my 15-91 for ruffles, tucks, etc., and my featherweight for quilt piecing. I also keep a Singer 66 threaded with dark thread, just in case anything dark needs sewing, lol!