Not the answer you are probably looking for but I posted this thread with some deals on the Xtherm. Actually I just looked and they only have the regular size anyway but worth checking out and keeping an eye on.
Do you like the xlite? I tried it the other day at rei and it sounded like I was laying on plastic grocery bags. Not sure how much I'd care in real use but in the store it sounded annoying.
They crinkle for sure but it gets better after you sleep on it a few nights. I love mine and I guess i'm so tired when I hit the hay it doesn't bother me. The warmth and small deflated size is worth a bit of noise. My son has one as well and doesn't use it much due to the noise. Buy one at REI and if you don't like it just take it back.
Others talking about the crinkling (like sleeping on potato chips) steered me away from the Xtherm initially. But after buying one and using it.....it's not even an issue for me. Yes, if you stand there and compress it with your hands it's crinkly, but when I sleep on it, it hasn't been an issue. The larges are tough to find at times, and now with the new ones coming out......they may be even tougher to find.
FWIW the new 2015 Xtherms are supposed to be quieter. I had the Xlite (and the original 1st gen Neoair) and the crinkling did not particularly bother me, but others may feel otherwise.
If you want, I can see if I can get a noise comparison between the XLite and XTherm that I have. I haven't actually had to use the XTherm myself in the field yet so I cannot speak to how the noise is different laying on it. I can say that I have slept on my XLite next to someone on the Xtherm and it didn't bother me. Then again, I have been in a tent with 3 of 4 people on XLites and the other on a Trekker and that noise didn't bother me either. Yes, you can hear them and yes, if you dwell on it, it may bother you. For me, I don't notice the crinkling any more than the sound of the materials rubbing together and any other sounds common in a tent. I honestly believe it is louder when you crinkle it in your hand at the store than when you are actually laying on it and adding pressure to the pad.
Also, I guess I should add that I have used my XLite exclusively with my 30* EE quilt down below freezing without issue. This last fall in Wyoming it turned out colder than expected. Granted, we did have a stove in the tent but that heat only lasted so long after we stopped feeding the fire. I did sleep in my merino underlayers and socks though so that did add to the warmth. When it's that cold, I don't want to have to take those under clothes off and on anyway. I guess I'm saying that for me, I'm comfortable with the lighter XLite down to some pretty cold temps. As with anything, it is all personal and depends on where you are going to be but unless you are planning to be in the really cold temps, an XLite might just serve you fine.
I have used an Xlite for a few years and have zero issue. My buddy picked one up when REI had the clearance on them. He never said the noise was an issue and I have never even considered it to be an issue. When the pads are aired up they don't make much noise imo.
I would assume the same will go for the Xtherm or even the Symat UL9.
I went with the UL 9. I haven't received it yet so can't attest to its ability. I can however say that Campsaver is an outstanding company to work with. Their customer service is great and they will beat competitors prices by 5%.