The first thing I noticed about the Femmecup is that it looks and feels like it's made out of plastic, not silicone. The body of the cup is very soft, and I think it would be a good choice for women who have problems with cups pressing on their bladders. The rim is of course stiffer. The stem is rather rigid, especially compared to my Keeper Mooncup, which has a flexible stem.
When I filled up my small Keeper Mooncup with water to the holes and poured it into the Femmecup for comparison, the water was exactly at Femmecup's 15ml mark. Since I know from the size charts that the small Keeper Mooncup doesn't hold 15 ml, it seems the Femmecup's measurement lines are off.