i switched from a zlite full length to a small neoair, and i've never woken up sore since. i still use the zlite under the neoair when im car camping or winter camping.
The neoair is SO much smaller, lighter, and much more comfortable. i got mine from campsaver when it was on sale, and i think it was around a $100 for everything back then (pad, sack, and repair kit). unfortunately, they've raised the price a bit...