I don't think it's a matter of Visa/Mastercard being hacked, but websites (or actual locations that accept them) are being hacked. Target, Home Depot, etc were all at fault, not the actual card companies themselves. I have no idea if the links to purchase via PayPal are more secure or not, but I highly doubt it. If someone screws up here at renderosity, then it's probably just as likely to affect any of them.

PayPal is NOT a bank. So, it's quite possible that they aren't required to go to as much trouble to protect you as the people that issue Visa and MasterCards. If there are disputed charges on a Visa card, you are legally protected against having to pay them (though, you may have to hassle with the bank to work it out). There are no guarantees that PayPal will honor your dispute, and I don't think there are any laws requiring them to do so.