First, let's look at the above expression "... tell the processor that this is a recurring transaction ... so you get a discount on transaction fees." The true cost of processing credit cards is the percentage and fee for each item based on the type of card presented (and some other factors that I will not delve into here). The fact is that for a wholesale price plan, the price will be the same, regardless of whether it is repeated or not, because there are no special rates for โrepeatingโ the exchange. But I was distracted.
"Any recommendations on the best method / service / gateway for implementing recurring billing?" Do not store credit card information, no matter what. You cannot afford responsibility. The right choice depends on several factors.
Regarding credit card portability, did anyone go to Wells Fargo / First Data and get the data? (Braintree ISO / MSP). I guarantee that this will not be the case no matter what, so I would focus on the right long-term solution, and not on the exit strategy, although it will certainly weigh.
Here are the questions you need to answer: How many transactions per month? For very small volumes, maybe a few hundred, select paypal pro. Easy to get in / out.
Are people more likely to pay with consumer cards or credit cards? Optimize sharing is important if business cards. (CenPOS automatically optimizes the transaction for minimal exchange qualifications, paypal and authorize.net do not)
What methods does my customer accept payments? do you pay online only? Phone bookings? Mobile payments (special events or retail)? Choose a gateway that meets all their needs.
Do you need to charge on certain days, that is, from 1st to 15th? Or anytime? If on certain days, how do you erupt? Check the response to gateway flexibility.
What happens when a card expires? What happens when a transaction is rejected? Who will need to see payment details for customer service? How will they be able to access it?
Identify your needs, then find out which ones match them. For recording, CenPOS is the most reliable solution, but may require additional steps for integration, as they are newer for e-commerce. Disclaimer: I was a business user of paypal and authorize.net, probably for a decade, and more recently, CenPOS. I am also a reseller of authorize.net and a direct agent of CenPOS.