I have run Sierra Designs bags for about 10 years. Their Arrowrock bags were some of the best ever made, much like the MontBell bags with the elastic. I currently have 3 SD bags, the Arrowrock 15, a 15 degree synthetic, and a 0 degree Zissou. I love their DriDown, but lately I've been turned off of SD because they seem to cater more to the hipster camper crowd than serious backpackers/outdoorsman. Nothing wrong with that approach, I just hate hipsters. So to answer your question, I've had very good luck with Sierra Designs bags, I feel they're quite innovative in their designs, especially the mobile mummy and backcountry bed bags.