@Thomas Baekdal the effect on sales is going to depend on your market and whether you completely move away from PayPal or just offer a second option. I can tell you that for Perch we offer both PayPal and credit card. Credit card payments are more than twice the number of PayPal ones, so generally people prefer not to use PayPal (and our market is essentially web designers and developers).

Before we moved we had a fair number of people asking if they could pay without using PayPal because they would not use it.