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Even without bitpay the currency risk is being massively exaggerated. How hard is it to send all your purchase coins to an exchange and hit the sell button a couple times a day? Honestly if a merchant gets only a few bitcoin orders this might be easier/cheaper than bitpay. Send coins to exchange and hit sell.
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Merchant doesn't even have to hit sell all the time.
For instance, on Mtgox you can setup a sell order say for million bitcoins at 1 cent or any other below average market price even with empty account and just send bitcoins to the exchange, which will be sold automatically to highest bidding orders once they reach exchange (~1 hour)