Gear Junkie here, I did some testing on the LD comfort and it was pretty amazing on the level of comfort I was able to achieve in the Arizona heat. I have lived here since 1967 and used to use a sweatshirt then I changed over to the LD comfort. I even use it for Mountain Biking. Check out the link on LD comfort
http://www.youtube.com/watch?v=Qn8NocCkbJw