"We investigated some traditional payment processors like Braintree and Authorize.net ... A lot of traditional gateways have long, complicated setup processes, often involving sales calls and working with banks. ... They also typically require you to send credit card data through your servers, which means obtaining a level of PCI Compliance (not that we aren't already security-conscious)."

I've used both of these. Braintree may not have been the right choice in their situation, but grouping them with Authorize.net for these reasons isn't really fair. Braintree's bundled merchant account and gateway services are much easier to set up, and their transparent redirect eliminates the need to handle card data on your own servers.

And in my experience, their "We (heart) developers" motto is, well, true. They have really great, friendly support. Braintree and Authorize.net are miles apart. At least as far apart as Stripe and PayPal.