Quoted from ForceFlow:Paypal's API ended up being too buggy to continue using, unfortunately. And paypal support didn't really respond when there was an issue.
Stripe (the payment processor in use right now) should support pretty much every card, including discover.
Paypal also isn't a bank...so they can just freeze your account for years and give no reason, and face no repercussions. Stripe is 100% better for buyers and sellers.