I saw a girl today and who was wearing a version of this in a heavy knit fabric with a fringe all around it. The armholes were a lot higher and cut like in a racerback top and they were very nicely finished.. This made the upper part of the circle not exactly a half circle but a bit smaller... as when you wear a round knit shawl, folded not quite in half. The armholes were not right in the center of the circle.... Also, the shawl collar covered her upper arms which made the lower part cling to her back giving it a very feminine, curvaceous look.
I plan on making one out of muslin before I hit the good boiled wool I have been saving for something special. This is it.... can't wait!!
Good luck, let me hear more comments, please.