stevesh:
It sounds like you're saying that 50% of your current customers use Paypal and 50% use Authorize.net ? I'd be interested in how you know that the visitors who used authorize.net wouldn't have bought from you if you only offered Paypal.
There is a long-standing Internet meme, especially prevalent among the self-described tech-savvy, that involves disparaging Paypal (also known as Slashdot Syndrome). I don't believe such an attitude is common among ordinary online shoppers.
I don't think anyone can answer that question definitively. I do know that 3 years ago the split was 5%/95% PP/CC and that number has changed to nearly 50/50 today for our online store which indicates that things are changing.
I do know that during that same timeframe one of our vendors which is a Warren Buffet/Berkshire Hathaway company was having a significant issue with abandoned carts. In attempt to find out why, they spent between $150,000 and $200,000 on a survey to address the issue. The overwhelming response was that being taken offsite for payment, whether PP or CC via PP site, was the reason for abandoned carts. There were business reasons for the initial implementation of PP only but after the survey, they quickly made changes to the business model and the results were significant and quick.
I can also say that I personally prefer to stay onsite when making payment for an online purchase. If I am taken offsite, I will probably complete the purchase but I find a different source for future purchases.
A similar analogy is used between shoppers using a MC/VS or an Amex card. Every Amex cardholder also has a MC/VS but they prefer to use the Amex card and will manytimes find a different merchant that will accept the Amex card for future purposes. Amex purchasers generally have higher ticket averages over MC/VS.
Does the survey apply to me? I don't know. I can't say definitively but given all of that, I like to make it easy for customers to spend money. Offering onsite CC acceptance costs about the same as accepting PayPal and in some months, the percentage is less than charged by PP considering all monthly costs to process the CC. PCI compliance is just a matter of scheduling a quarterly scan, though I have the scans performed monthly so that if there ever is a problem, I have 2 months before the current scan expires. We pay no monthly, quarterly or annual compliance fee and our host usually has any issues corrected and approved before we even know they exist.