I vote for option 2 but leave the gap between the insulation and the featherboard. That way you can allow airflow and have space for any water that may get through the feather board or roof to drain out.
Will the shed be heated or cooled or are you just trying to reduce the temperature swings?
+1 for option 2. Option 1 is a snake oil, won't do anything or next to nothing. Website doesn't even provide the thermal conductivity of the material..
I vote for option 2 but leave the gap between the insulation and the featherboard. That way you can allow airflow and have space for any water that may get through the feather board or roof to drain out.
Will the shed be heated or cooled or are you just trying to reduce the temperature swings?