If you're not using Spreedly, I recommend it because it's a big help in this situation because it allows you to seamlessly switch services without losing any of your customer card data.
Strongest possible +1 for this. I did a live migration from Paypal to Stripe in under 30 seconds once. Spreedly made this as easy as flipping a configuration switch. As far as I can tell, we didn't lose any business as a result of the migration.
I don't see any reason I'd ever move off Stripe (+) but it's more than worth just preserving the convenient-doesn't-require-app-rewrite option to do so.
+ Edit to add: Ooh, got one: an acquirer can dictate a move to their favored/house processor as a term of an acquisition, and "Sure, give me six weeks to do engineering work" is not something you want to have to worry about when putting that deal together.
Our gateway support is heavily influenced by customers, so anyone who has a gateway they'd like to pass bank account info to that we don't support today shouldn't hesitate to drop us a line.