I use a NeoairXlite, and I don't know about you but my shoulders always get cold. And that's with the 25" wide one. I supplement it with a Thermarest folding Zlite cut in half. It's the perfect size to wrap around the Xlite and keep your shoulders warm.
I'm continuing on my AT hike next spring and may switch to this system instead of an underquilt. I never had to go to ground in 550 miles but if I had an air mattress I would have considered sleeping in a shelter during a couple of downpours. It's a heavier system but it gives you more options.