Looks great! One thing: Please don't force me to host my stuff with you. I'd rather pay twice to have the freedom to dl my designs. Also: Let me pay-as-I-go. As a designer I'd like to use this but I would not want to pay X bucks per month. I would pay X dollars per project.
Edit: After studying the video: I'll pay triple! Any thoughts on importing bootstrap?
We're actually big fans of the MailChimp pricing model (both pay-as-you go and monthly options), so it's a possibility.
About Bootstrap, the current demo already uses it for the non-visual elements (grid, etc), but we're still not sure about a whole-scale import yet. There are a lot of changes afoot with Bootstrap and Foundation (mobile-first being a big trend), so we're noodling on a ton of options.
Great work! I agree that importing a current site/design would be a killer feature. But, forcing to host is a non-starter...and would probably cause more issues for your company as well.