I heard that if the pledges come through Prefundia , that they keep all the backers details so in the long term, you are building their brand awareness, instead of yours. (Shrug) I'm pretty new at this marketing thign and Prefundia seems easy enough to set up...
I tried them out pre-launch on my first campaign. It was hard to tell what backers came in via the email list and which ones came from prefundia, but my estimation was that it was not very many.
Over 10 projects created, launched, and funded. Most recent campaign: http://bit.ly/1io3HZh