This is a follow up of an older topic.
The original topic is pressing the importance of adding AutoCompleteType="Disabled" to all sensitive input fields. Taking that a step further, autocomplete="off" should also be specified on such fields as only Internet Explorer turns off autocompletion for fields marked with AutoCompleteType="Disabled", while FireFox and other browsers continue to remember and suggest inputs.
As it stands now in nopCommerce 1.8, all 10 payment providers which accept credit card numbers will store any number entered in the autocomplete history of FireFox.