You can sometimes get soy-free miso tamari from South River Miso (www.southrivermiso.com). There are several flavors, and they only have one flavor available at a time, when they have it in stock. It's also a living food, unlike Bragg's. However, it's a specialty item that you probably don't want to make a staple due to its price and lack of availability--South River Miso doesn't ship between late April and September or so.
I agree that you can do without it. Sometimes I'll mix miso (also available soy-free) with water and some extra salt to substitute for Braggs or Nama Shoyu. Often just adding salt to the recipe is sufficient.