asking this as an ex-Rocket guy with my own startup that needs payment integration soon. I've started the Paymill process but not sent the docs in yet.
- https://stripe.com/chat VS email
-You usually don't need to "send the docs in" (being hungarian, they asked for my ID, but email was fine), which reduces time to launch
-After having launched with Paymill, production started throwing strange errors. Root cause analysis revealed, that they don't have USD / EUR acceptance enabled by default; and they asked for extra paperwork to have that. This is not a good problem to have when users are hitting the payment wall.
One thing we've hit is that there's a requirement to specify the first amount you're going to charge (which you might not know at that point) when you get a customer's CC data, that can be a real pain.