From another source regarding styro:
Although they definitely have short-term thermal insulation benefits over pulp (egg carton), corrugated (Gorilla Shipper) or plastic tray shippers, it's a temporary benefit. Sure, if the wine starts out cool from the point of origin, the polystyrene shipper will keep the bottles cooler for the first few hours, on a warm day, over the other packing materials. However, if the wine is sitting on a truck all day in 87 degree (random temp) weather, eventually the bottles are going to warm up to the ambient temperature. In polystyrene shippers, the bottles will stay warm longer after it cools down at night than if the bottles had been packed in a pulp, corrugated or plastic tray shippers. So, if you receive wine in polystyrene late in the day on a hot day, open that box up quickly and get the bottles into a cooler place.