Earlier quoted context omitted.
Most large Stripe clients split traffic. It doesn't make sense to have Stripe be a single point of failure if you're processing enough volume.
How do you do that when Stripe holds your subscription / recurring revenue? Keep that recurring revenue base independent of the CC processor? I used to use Recurly and stuff like that but it seemed like I was paying double just for the benefit of maintaining my own recurring charge list, not to mention not integrated with many of the payment features.
Yes. You can transition existing customers over time by moving them over when their card expires.