I used to offer my clients the option of Paypal or a merchant payment service via Authorize.net.
About 75% chose Authorize.net and 25% chose Paypal. I noticed that the disputes, claims and charge backs on the 25% of paypal users was just as high if not higher some months than the merchant payment gateway.
But I bought into the Paypal hype that using Paypal would increase my sales by 20%.
I had a problem and I had my paypal pw stolen and had to suspend my account for about 2 months until Paypal could resolve it..
I only offered Authorize.net.. .. I noticed right away that the "aborted" sales dropped down to almost nothing and my sales actually went UP!
It seems that buyers were coming to my site, accidentally choosing the paypal option and when they saw that they had to join or sign up they were aborting the sale and leaving.
Now that I only use authorize.net I barely get any aborted sales at all.
Also I know most of you give 100% refunds upon requests but I don't and I dispute just about all charge backs. Disputing a charge back with a merchant payment processor is a piece of cake. It's 1 fax and the money is back in my bank in 14 days TOPS. With Paypal it was a nightmare with tracking numbers and sometimes it would take 6 months for the money to be returned.