I have the Megamat 10LXW; it’s great and the trade offs for it are very small, in my opinion.
The only other mat comparable I would and have considered is the Thermarest MondoKing 3D. I actually bought one, laid it next to the Exped, tried it for a few hours, etc but found that while it’s every bit as comfortable, I didn’t care for the valves, which seem to be the biggest turnoff for that mattress, taking forever to inflate and deflate, compared to the Megamat.
The Megamat just has better valves, it’s easier to inflate/deflate and that was the winner for me. You can even speed this up by getting a $12 air mattress inflator from Walmart which works on 12v and completely fills the mattress (over inflates, actually, I usually find myself letting some out) in about 30-45 seconds.
For duo camping, I borrowed a friend’s Exped and used the coupler kit they sell to link the two together. This worked exceptionally well and gives you even more space than the duo (two 10LXWs next to each other is a queen size mattress equivalent), so you can also couple the mattresses and then throw a queen fitted sheet over them for even more posh comfort. I prefer the $15 one from Target (Threshold or something?) which has two sets of elastic and seems to stay on the best I’ve found. The twin also fits on a single nicely as well. Another huge benefit is being able to set each mattress to different firmness so you can each sleep peacefully, whether embracing or sleeping spaced apart; like a sleep number setup, but for the outdoors.
Other benefits might include setting the mattresses up like a futon for a ground couch when not in use as a bed (which I’ve seen but never tried myself), single use for solo trips which don’t include a partner, etc.
There’s also the fact that you can stack the mattresses to make a super cushy single mattress if you’re going solo and feel the need to treat yo self.
It costs more, but if I feel the two separate mattresses is a total win. Besides, they pop up for reasonable enough deals on various websites from time to time. I think I got mine for $160 or right around there.