I purchased an Exped Downmat Winterlite from REI the day they became available. The specs are quite impressive from a BPL standpoint (I got the Long-Wide model; I am 6' 185#)
-R value = 7*
-25.6"W x 77.6"W
-23.5oz
-2-way valve
-Included pump sack ('schnozzel')
After using the mat on a few trips I was quite disappointed with the mat and cannot recommend it. I'll preface this by saying that this is a very premium mat at $250. Prior to this mat I had an Xtherm, and this mat should be even warmer with +1.3 r value. However, each time I used the mat, my heels and elbows would get cold while the rest of my body was warm. I figured my body was just struggling to initially warm the down in 35-40F temperatures. Also, despite this being the LW model, it's only marginally wider and just appreciably longer than a regular size tapered Xtherm. Judging by the specs the LW Winterlite should be luxuriously large for someone my size, but I found that my feet would constantly slide off the tapered sides. Part of this is due to the extremely slick material on the top of the pad. I figured this would be quieter than my old noisy Xtherm, but the slick surface makes a lot of noise against baselayers or a quilt.
Unsurprisingly, I returned the mat today. I just received the 2015 TaR Neoair Xtherm Max LW and compared it with the Winterlite to be sure. During this comparision I figured out why my feet and elbows were getting cold. I also discovered what is IMO, a huge design flaw and some surprising corner cutting on Exped's part.
I knew from another user's Synmat Hyperlite review that the insulation doesn't cover the entire mat, but his is excessive:
ZERO insulation along the sides of the mat. What's the purpose of it being a wide insulated mat?

Here's why my heels were freezing cold each time I used the mat. ZERO insulation right where my heels rested

Even in the insulated area the down shifts to the point that 'holes' where there is no insulation form. There's no way to know if there are holes (so you can shift the down back to cover them) unless you have a backlight behind the mat.

Another criticism I have are that oil/sweat/moisture stains the mat almost immediately unless you are perfectly clean – something that's not the case when you're backpacking.
The Downmat is VERY warm where insulated and it's wonderfully easy to fill up using the included schnozzel pump sack. However, the TaR Neoair Xtherm wins on space, weight, durability, maintenance, and price – $229 vs $249.
Here's a few comparoson shots between the DM Winterlite, TaR Xtherm Max LW, and Tar Xtherm Regular (2014):



DM Winterlite Weighs in slightly overweight at 24.05oz (23.5 claimed):
Xtherm Max LW weighs in underweight at 21.40oz (23oz claimed):
The schnozzel is still quicker and way easier to fill the Downmat, but notably the new Xtherm Max comes with a much larger pump sack than the 2014 version, in addition to a normal stuff sack. It took me about 5-6 fills of the larger pump sack to fill the Xtherm:
Schnozzel:

New, larger pump sack for Xtherm:

Stuff sack for Xtherm:
Despite having claimed lengths of 77.6 (DM) and 77 (Xtherm), the Xtherm is in reality a good 1" to 1.5" longer than the Downmat. It's a bit curious since the DM is supposed to be 6/10" longer, but the Xtherm's slight extra length is welcome. If you're 6' tall like me you can lay on your stomach with your feet stretched all the way out and remain on the mat.

Finally, here are some close up shots showing the material and texture of the mats. 2014 Xtherm, Dowmnat Winterlite, and Xtherm Max, respectively. Both sides of the 2014 Xtherm have a soft feel, possibly due to a urethane coating according to one reviewer, while the Downmat and Xtherm Max have harder-feel materials. The 2014 Xtherm has the most grip and the Downmat is the most slick.








