The difference between your Z-Lite and the Neo Air, size small, is 5 ounces. For me that's a significant weight difference. Ounces saved here and there add up to pounds saved, and ultimately to a much lighter pack.
The Neo Air, size small, weighs only 9oz. small Neo Air
This should not be confused with the Neo Air Trekker, which is a heavier pad, and the size small weighs 16 oz.
If I'm going to be in conditions that require more insulation, I can also carry a Gossamer Gear, Thinlight pad. So I would get some added warmth for the extra 5 ounces.