I have been baking successful gluten free bread for a while now ( http://www.recipesforliving.info  ) and finally decided to take up the challenge of sourdough. My starter uses a mix of 2/3 buckwheat flour 1/3 brown rice flour (following the method provided by SourDom (thanks!)
Gluten free flour mixes tend to be very thirsty, so I think my results may be due to the hydration as well as over proving. Working on both issues for the next batch!
The crust tastes good, but the uncooked innards are a bit strong. I cooked at 40 minutes 210 oC, but extended that out by another 40 minutes when I realised something was wrong.