We actually had the luxury of comparing parallel efforts. While Node was being readied for production we were writing our new consumer/wallet app with the PayPal Java framework (based on Spring). Meanwhile we started writing the Node version. Once we got to a certain point the Java team insisted that they stop the Java development and start on Node with the node team. At this point we had two versions of the app built in two stacks and thus could compare code size, developer productivity & scale.
Of course, if we compare the new node apps vs the old PayPal code... well that would be a poor comparison as they really were old and monolithic.
Of course, if we compare the new node apps vs the old PayPal code... well that would be a poor comparison as they really were old and monolithic.