It could be valuable to have a feature grid kind of page where you compare your platform to the built-in subscriptions in Braintree and Stripe, to provide an explicit list of the things you can handle that they can't.
Yeah, for example, see MailChimp's feature table for their Mandrill service that allows prospective customers to compare Mandrill to SendGrid (the market leader?):
https://www.mandrill.com/features/
I definitely prefer pages like that.