Light buckwheat flour vs dark

Light buckwheat flour is processed so the hull is removed and the dark or black buckwheat flour is unhulled. What about the pyramid-shaped groats that look green in colour? They too are the hulled version, that is good to grind into flour. White buckwheat groats are the hulled version of whole buckwheat.  

I have always bought the light version of buckwheat flour at supermarkets in Sweden, the UK and Australia. Last month I bought a cheaper bag of buckwheat flour at the Oriental shop and when I opened the packet it was dark black buckwheat. I could use it in my recipes however I baked bread and didn't enjoy the taste or texture and tried making crepes and once again the texture and taste were strange. In my crepe recipe, I added about 3 tablespoons of light starch flour like potato starch or cornflour/ cornstarch to help but I still wasn't happy with the recipe.