One thing they don't mention is how buyers come into possession of bitcoins. Buying bitcoins is currently a hassle for an average consumer and has transactional fees that are paid to bitcoin exchanges - enterprises of unknown origin and reputation that don't have household level brand name recognition (ask your aunt Sally or uncle Kamal about Mt. Gox).
I assume that chargebacks that are offloaded to bitcoin exchanges. These exchanges are the weakest point of the bitcoin ecosystem at the moment - this is where bitcoins touch the real world.
Contact with the real world makes them susceptible to the control of the authorities (regulators, law enforcement, criminals and etc), easy target for malicious parties meaning harm (yes, don't want to use the word hackers) as well as financial manipulators.
Success of BitPay and the like depends on the health and stability of the whole ecosystem, which is still quite immature, so if I were a merchant I'd approach this cautiously.