"gateways, processors, and PCI compliance"

These are not that complex and should be well-understood by any would-be entrepreneur. We are writing our own recurring billing system right now for our startup www.wellhubstudios.com, using Auth.net CIM. Auth.net even offers recurring billing themselves. Another obvious issue with the services you mention such as Chargify et al is that they charge a higher rate for each transaction than most other Merchant Account providers, sometimes 1-2% more per transaction which, if your trying to run a viable business based on margins it is something to greatly consider. The Transaction fee we got was ridiculously low compared to what these "recurring billing" apps (which surely will reduce your headache) are offering. Off to make some money.....