I have the Xtherm and its warmth is incredible.
What I don't like about it is I am a side sleeper and like to curl up into a ball. For this, the regular Xtherms are too narrow for me. I looked into the wide/Max Xtherms but they are north of $220.
What I got instead is the Exped Synmat Winterlite in size "M Wide" that is very comparable to the Xtherm max line in terms of weight, width and R value but costs $100 less.
http://sectionhiker.com/exped-synmat-winterlite-sleeping-pad-review/The Exped is actually wider than the Max by an inch. The extra width from a regular, 20" pad does not seem like much on paper but it is a huge difference for me when in actual use - nonlonger feeling like I am sleeping on a 2x4.
