Personally, I find the neoair very loud and crunchy sounding, therefore, I'm a fan of the Exped line. The downmat is great if you will be in colder than 20 degree temps, but the synmat is fine for anything else. Just slept on the synmat last night in the low 30s and I was toasty warm (and I'm a cold sleeper!).
You can buy the synmat from REI, test it out, and if it's not warm enough, exchange for the downmat. The synmat has the advantage of being lighter.