Most of the gateway-style services operate very similarly. We wrote some abstractions to allow us to eventually add Braintree or Authorize.net, since the payment cycles are much alike (from the API perspective). It only gets difficult when you try to mix-and-match something that uses redirects/iframes with services that deal directly with credit cards from your server to theirs.

We just don't want to get into PCI audits and scans just yet, but once we do, we'll probably use Stripe's direct server->server APIs like Braintree/Authorize.net do instead of stripe.js.