Replace PayPal with the name of any bank offering merchant accounts, or any MSP (they're all underwritten by a bank at the end), and the post would've read exactly the same. Every merchant account agreement reads the same -- if anything causes them to consider your account a higher risk than when it was first approved, they can open a reserve account and hold your money. If they suspend your account they will hold your money for exactly 6 months. It's the same everywhere.

These aren't things to consider when using PayPal, they're things to consider when you start accepting credit cards through anyone. You must plan for the possibility of having your account suspended at any time and for having whatever money hasn't yet been paid to you held for 6 months. Know who you're going to turn to if it happens and, if you've got the development time, integrate it with your site and be ready to turn it on when needed.

Here's a business idea for HN: build a payment platform that's processor/gateway agnostic. It'll need to have an API for directly taking credit cards, then pass that on to whatever payment processor you've plugged into it to make the charge. It'll also need an API to generate payment buttons for 3rd party processors like PayPal and Google Checkout. If one of them closes your account, you just plug in the login credentials of another and your website keeps running without changing any code. The recurring-payments-as-a-platform providers are half way there, but there's plenty of space for a different abstraction that doesn't focus on recurring payments.

I've already done so many payment integrations I probably have most of the code to create such a service, but the security and legal stuff you'd need to handle are significant enough that it really needs to be a full-fledged startup, not a side project.