Sort List<DateTime> Descending
Though it's untested...
docs.Sort((x, y) => y.StoredDate.CompareTo(x.StoredDate));
should be the opposite of what you originally had.
What's wrong with:
docs.OrderByDescending(d => d.StoredDate);
docs.Sort((x, y) => y.StoredDate.CompareTo(x.StoredDate));
Should do what you're looking for.
docs.Sort((x, y) => -x.StoredDate.CompareTo(y.StoredDate));
Note the minus sign.