The FAQ on the Kickstarter page was a little misleading. The question was why back the game instead of waiting for retail. The answer was to get 6 themes instead of 4. So it seemed that Kickstarter version would have 6 themes and retail would have 4.
A number of people have made that assumption, but Good Games have clearly stated the same position since the start of the Kickstarter - the retail version will have the same decks, but not the teasers. They have also said they are happy for people to purchase retail and would like people to support their FLGS. So its up to you.
BTW, the FAQ says
you and everyone else can get 6 theme packs instead of 4, saving $20 , gaining 5 player mode and more replay value.