I vacuum pack my emergency supplies such as cotton fire tender and gauze to minimize their size. I did a little test and vaccum packed my bivvy and a few other items just to see how much smaller they would be. The results were impressive, but once an item is opened in the field the space savings are lost unless you happened to have packed a vacuum pump. Have any of you guys investigated the trade-off between the space savings of vacuum packing your gear vs the extra weight and space of packing a vacuum pump?