The CPayment.CreditCardNumber property throws an exception after upgrading to 15.1.2.x. See two attached files for a console application and config file that test that everything is working correctly.
... Yes, this is a working example once we got gor our upgrade issues resolved. As stated in the comments below, you'll need to remove the BindingRedirect section in the config file to use the older imis 15 version of the payflowpro assembly.