Code against SpreedlyCore and you can point your account at Stripe, SagePay, PayPal, or whoever offers you the best rates at the time. If PayPal burns you, you change one variable in your code and all your payments hit a different payment processor. The differences between all the payment APIs are abstracted away from you, and similar to Stripe/PayPal, payment data never touches your server so most of the PCIDSS compliance burden disappears... yet customers never leave your site, either.