At the risk of bucking the trend? I have a new 9DLX that I got for the now cancelled artic exped. It's okay- yes it's comfy and warm, but it's bulky and heavy (1.2kg). Not much difference in weight between the 7 and 9, so I went for the 9 but I am too broad for the standard width ones. They take an age to blow up, well compared to flopping out a mat anyway.
People talk about comfort? Yes I want to be comfortable but TBH I'm comfortable with a foam mat. If I want comfort I'd be in a B&B!
If I were buying for the arctic again, I'd probably just use one of my 4 season foam mats and an existing self inflating mat together. Both (together) are lighter that the 9DLX, as comfortable and though much bulkier (foam mat), it can be happily strapped outside the bergen. The foam mat will also totally remove any fears (although it hasn't happened) of puncturing £105 worth of mat. Just my 2p worth.