Dunno much about these kites, but read the reviews on the 2015 one and see if the changes are significant and would suit you. Then go over the 2015 one, making sure its still crispy, lines are still waxy, the list goes on - if you don't know what to look for get a mate to help. If the 2015 one looks like it has minimal wear I would go that route, and try and get a 1 year warranty out of the shop for it, this might be tough as it is demo but they could get a good deal going for you. if you go the 2013 route it should come with atlas 1 year warranty.
Good luck, at the end of the day either kite would be awesome

thanks very much for your imput I am leaning towards the 15

Thanks guys, i feel the 15 is the better choice so will be picking it up this arvo after an inspection. As a newbie it isvery difficult to make the brand choice. Yes resale is also a huge factor my mate only buys cabrinha because they re sale well i also liked the Nash pivot too. seems to me that kite choice is a never ending process that i am just going to have to get used too