I used to have an MSR pack with the ultimate in ventilated backs. There was a grid of nylon cord that went against my back and the sack of the backback was 1 to 2 inches removed from my back. Sounds great right?

Well here's what happened with me, a heavy sweater. My back would get soaked from sweat. Air would run up my back between the pack bag and the grid of nylon cord. The result was that I got cold.

In otherwords, the venting was not able to prevent the sweating but it allowed circulating air to uncomfotably cool my back.

Soooo, will the eggcrate work for you? I don't know. Try it and tell us your story.