I've considered doing something similar for my own side project, but went with the more standard sign up because I was worried it would be confusing (as it was to me, for a few minutes). Do you guys think this is becoming more mainstream, at least amongst developers and the tech-savvy, that other projects could get away with this? I'm curious how many support requests Stripe gets because of this.
Edited to add: How does this work for the non-logged-in state? I already have an account, and the browser cookie expires (or manually delete the cookies). I'll go to the dashboard, and be logged in as "anonymous", and have to sign out and sign in again as the right user. Seems like an extra incongruous step.