Earlier quoted context omitted.
Recurly is not a payment processor / merchant account. It is just subscription billing logic as a service, sitting on top of your actual processor.
They do provide a payment gateway, but you have to have a separate merchant account. The gateway is a relatively new feature.
Gateways are themselves just more APIs. They don't have much, if any, impact on the "zero hassle" question you asked, which is all about the lack of an application/underwriting process compared to getting a merchant account. There's no separate application/underwriting for getting gateway accounts, your MAP typically resells one or more and just gives you credentials once you're through the MA underwriting and get account numbers to attach to it. Recurly doesn't save you from that at all.