To give an example I sell my software through Avangate, this results in a single invoice and payment each month. I know if I switched to Stripe it would save my a couple of percentage points on each sale but then I'd need to maintain systems that handled EU VAT laws, issue license codes and import a lot of data into my accounting system, in fact I'd need to upgrade my accounting system which is fine with a few transactions each month but would be stretched at fifty or more.

This has been my experience with most of these services, great if you want to grow a large business because you are effectively outsourcing some of your work but it does tend to complicate things. Personally I like my work to be small and simple.