I have one......But I am considering ditching it. I will be doing Deaths Hollow from July 11th-14th (15? 13?).....I have my gear all collected, food gathered. I am going to try using a US GI surplus poncho liner instead of a sleeping bag, because all the reviews I have read say that these things will keep you warm or cool, and I can attest that they are extremely light weight. I don't have to have cushion when I sleep, and I'll be on the ground anyway....I don't remember it getting that cold at night the last time I was there.....So is an earth mat really needed? Will I freeze to death without one?