No - I do not agree.  The bidirectional board is gives better windward performance than unidirectional rudders.  The bidirectional board is better than rotating rudders because the rudders are symmetrical foils so will be less efficient at generating lift than the board designed for a narrow range close to zero AoA.  We aimed for 3mm radius on the edges of the board and achieved close to that.  The unidirectional rudders were built at a boat yard and actually have thicker trailing edges thicker than that.   It is not unusual for unidirectional rudders with a 500 chord having a trailing edge with larger radius than 3mm.