I have had the Thermarest mondo King, Megamat XXL and Megamat duo by exped.
I owned many (7) thermarest camp rests In the past 2.5 inches thick, and have one smaller thermarest for lightweight camping.
Here's my take. I used the Megamat duo for car camping in a Tesla Model X 5 seater. The mat is a bit too wide and almost too long, the mondo King is also way too long as you can barely close the trunk unless it is slightly angled. The mega mat 10 is nearly ideal.
The mondo King is almost impossible to deflate . It is not " cored foam" like the Exped and so it is not only heavier but the foam also resists compression so much that the last 2 feet of mattress is so hard to deflate while the rest wants to reinflate.
I'm 187 lbs and couldn't do it. A 210 lb REI employee could not deflate it either when I returned it.
I like the Exped Megamat 10 XXL because it is super easy to inflate and deflate, easy to fold and ultimately more comparable a surface for sleeping, the valves don't stick out ( so they don't get stepped on and cracked) and the inflator puff is a easy to use.
The Megamat duo is harder to deflate , considerably more so. But the space is wonderful. it's almost a full size bed. Now,,,,,, if you want to go wild, you take a Megamat duo and a Megamat 10 XXL and you can create a 77.25 X 82" mat , the same size as A KING SIZE BED, to which I add (2) 3" foam mattress toppers that can cover a king sized bed, making t ,, simply the most comfortable wilderness sleep ever....that's luxury.
So if you have to inflate and deflate this more than say 2 times a week, do not get the mondo King. If you have to deflate it more twhen 4 times a week you might not want the Megamat duo , and if you deflate 5 or more times a week you gotta get eh Exped mega Matt 10 XXL which at 30" is pretty wide.
The best use of the mondo King was as a pool float , just narrow enough so a girl is almost on top of you if you share it.
The valves SUCK ON THE MONDO KING they are slow to fill and drain. Now, if you do crack one, it is probably easier to fix than w bad Valve on a Megamat.
Date published: 2018-02-14