My direct experience is with cause-related crowdfunding campaigns, but I've done a lot of research on the space in general.
None of the different platforms provide strong data around their ability to drive traffic (or purchasers) to your campaign, and I have to believe (if that were the case) they would go to great lengths to advertise that fact. The key things to consider are:
- Product: the social & referral tracking tools, usability of the platform, etc. - on this dimension, I like Indiegogo
- Credibility: really important for ecommerce in general, and even more so for brand new products - Indiegogo or Kickstarter would help in this dimension
- Fees: they can vary pretty significantly from one platform to the next. Crowdtilt (at the moment) has a white label platform (CT Open) that's virtually free (only take 2.5% for processing), compared to 7-10% of some of the other sites.
In my opinion, the difference between all-or-nothing vs. flex funding isn't too significant; it's better to set an appropriate target amount and run the campaign properly.
If you have a strong network/community in place prior to launching the campaign, it might be worth saving on the fees and using Crowdtilt Open. If not, it probably makes sense to go with IGG or Kickstarter.