Had a downmat 9 for almost 2 years now. It went to the top of Denali with me and kept me toasty warm. I'm guessing Luke (with the pictures above) had a leak or didn't have it inflated all the way. My experience in -15F at 17k feet was very comfortable.
*Mat is just the right length for someone 5'10 or shorter. Over that, get the long.
*Width is just perfect for me (I have wide shoulders and wear a small t-shirt - just barely :-)
*It does take a long time to inflate, especially at altitude. Uncorking the hand pump and the deflate valve and letting it sit for a while before inflating does help a lot
*I had three different baffles on my pad burst, but Exped was SUPER great on the customer service and mailed me out a new one almost immediately. They really stand behind their products.
*Downmat 9 is probably too heavy for even most winter camping. Save the weight and go with the 7 unless you are doing expedition.
*The shell is really tough. I have no worries about ever popping it on something.