Rating: 5 / 5
Like Dylan Carlson, I also used a Neo-Air (size regular for me) on a thru-hike. My thru-hike was of the Appalachian Trail, starting in late February (2010), so a lot of snow and cold weather in the first month or two.
I had a similar number of days on the trail too, but given the nature of the AT, I'm sure I spent less nights on the Neo-Air than Dylan did on the CDT (lots of towns, hostels on the AT ...). Still, I might have spent on the order of 100 nights on it this year.
Mine is still in great shape, I never had a leak, slow or otherwise. Given anticipated cold weather, I started the trip with a pair of Gossamer Gear thinlight pads, one 1/8" and one 1/4" thick. Depending on temperature I'd put one or the other of those below the neo-air and the other one on top. After I got done with the snow, I mailed home the 1/4" pad and kept the 1/8" pad throughout just to protect the neo-air. On the PCT and now the AT I've never had a leak or puncture, as I always have some sort of protection underneath my inflatables (i.e., I agree with Dylan on that one too). The thinlight pads aren't as long as the 72" neo-air, but I also keep a 1/3 section of a GG "nightlight" pad just as a sitpad, and I used that at night under the neo-air to cover most of what the thinlight did not.
With the combo thinlight pads I was always warm enough in my 20F Western Mountaineering down bag, albeit with additional clothing on (Feathered Friends down booties, Montbell Alpinelite parka) inside the bag when it got pretty cold --- down into the teens (Farenheit) multiple times.
I never had to reinflate the sleeping pad --- for me, at any rate, I always fully inflated the pad (a firm pad felt better to my back) and it was always still firm in the morning.
Obviously I had no "durability" problems, I suspect I put more use on that pad this year than many (most?) people will put on one in a lifetime, and at this point I'm thinking I'll use it on the CDT next year (toying with the idea of moving to the shorter version though). The one area of concern for me is the valve, and that because of the way it packs --- roll it up and the valve sort of sticks out, it seems like a point that could get more stress just in the nature of "shoving stuff down into the pack". But for around 100 nights this year I did just that and the pad still works fine, FWIW.
The "crinkly noise" was never an issue for me, and I suspect that it's less noisy now that I've used it quite a bit (not certain).