LOL @ FUDders who claim this will doom bitcoin b/c merchants.
One double-spend in entire history of BTC vs thousands and thousands of fraudulent doublespends (chargebacks) via MASTERCARD VISA PAYPAL etc etc etc. Not only that, but fraudulent chargebacks are practically encouraged by card companies, are built into the system i.e. you can request one. BTC allows no official channel for chargebacks and the only reason that one ever happened was because of a software fluke, virtually the only significant software fluke so far, which is pretty good for a piece of software that handles millions of dollars.
Do these FUDpeople just not think?
If I were a merchant I'd be glad to use a payment service with such a low risk of double-spends. Give me bitcoin with its 1 accidental $10,000 double-spend any day over Mastercard/Visa/Paypal/Amex/Etc with its cumulative millions of intentional double-spends and double spend feature available on request via official channel.
The only way we could dissuade merchants from adopting bitcoin is by introducing a double-spend feature into the client where you could request that a centralized authority charge back your money from a merchant. Then it'd be just like the credit cards. Oh and jack the fee to like 5%. THAT would be a great way to deter merchants. Not a fluke block-chain fork that is fixed immediately.
Some of your points are reasonable. Paypal loses a lot of money to fraud each year for example. But your point about 1 accidental $10,000 double spend is laughably ridiculous. You don't think that would have been a much bigger problem if btc was used widespread and people didn't realize what was going on as quickly? I guarantee there would have been LOTS of money double spent in that situation.