I think we are going to offer it under backer.app.net/project-name. It's something worth testing I think.

fwiw I have personally witnessed a significant percentage of consumers accusing a crowdfunding project of being a "scam" if it is hosted on their own domain rather than an impartial 3rd party like Kickstarter. I think that is one of the reasons consumers like Kickstarter vs self-hosted crowdfunding.

Additionally, in the Bitcoin use-case, if you have a page on your subdomain powered by Backer that accept Bitcoin, consumers will be confused and angrily say that you already accept Bitcoin because that page exists. That is also something we learned first-hand.