During my last trip out a few weeks ago, my MSR whisperlite failed again--due to cold temps. I know all about keeping the pump warm, but that is not a reality while climbing. So I got to watch Neils stove work perfect, while mine just added weight to my pack. So I bought the stove I watched work flawlessly. It came today, and it is 12 degrees F in my backyard. So I unpacked it, and fired it up and boiled a quart of water in about 3 minutes. Then I left it out on my table for 4 hours while I went hiking with my dog. The base froze to the table, so I know it was cold enough for my little test. I turned the fuel bottle back over(thier way of on-off) and pumped it up. It worked like a freakin' champ. This is the cold weather stove I've been thinking about since last years winter gathering at the loj. It does say that the fuel line gets iffy at -20F, but it will work, just be careful handling it. So this stove gets a 3 thumbs up rating for winter backpacking. It gets the official test in 15 more days at uphill lean-to.