I was wondering if any of you guys have this sleeping bag or know much about it? Its a good bit cheaper than the marmot, BA and WM bags I was looking at. It's pretty heavy at 4lbs but I think i can handle that weight and still make my benchmark. It also has a synthetic fill instead of down. It's over $250 cheaper than the others so I was wondering if it's that much lesser of a bag or are the others just more expensive because there lighter. Thanks!