I’m a one man dev shop but in an app I’m developing I decided to implement payments with two (or more!) processors with the ability to set a weight for each. It hasn’t launched yet but the current plan is to have about 90% or so of transactions flow through Stripe with the other 10% being a “hot backup”, more or less. If anything happens, I can just flip over to the other processor. I decided to actually have the second processor take a small amount of payments so there is less of a risk of it not working seamlessly in the event of a crisis with Stripe. It’s going to cost slightly more in transaction fees but I think it’s worth it.