It is possible to fly a symetric like an asymetric. I'm hoping to do just that myself. With just me and my wife deploying a symetric with the huge pole is just not practical without an extra set of hands. One person with a sock can easily handle it while a second person steers the boat.
I have a few club friends that claim you don't need the tacker if you just set up a downhaul off as forward a point as possible off the bow and above the rail, but you do really need the sock. The ATN Sock is probably the best you can get and handles quite well. Without a sock you have a whole lot of sail to manage.
You won't perform as well as a properly deployed symetric but you can get a lot of down wind light air use out of the sail if you already have a symetric and don't want to purchase a new asymetric sail. I would still want a sock.