- With AM, you have to accept the credit card details (even if you don't store them), and then send them on the the payment gateway. Even with AM's Stripe implementation, it's your Rails app sending the info to Stripe. There is no Javascript sending the details straight from the user's browser. (Or am I mistaken about that?) So you have a higher PCI burden than if you used Stripe in the normal way.
- AM doesn't provide any persistence, just an API to the payment gateway, so you would still have to roll you own tables/models for payment success/failure.
- I don't see support in AM for subscriptions.
Looking at AM again now, perhaps my previous comment was too harsh, although that's how I remember it when I checked it out long ago. Even now, I'm tempted to say that Payola's landing page already has better documentation than AM.