I wonder if there could be a way to convince BitPay to implement the best of both worlds here? Whenever a purchase is made, don't put an immediate-sell order on the market, but just place a bid (offering the customer a small discount in exchange for a small delay to confirm the transaction maybe?).
I think what Bitpay should be doing is selling payroll solutions to merchants that integrate BTC at POS side. This would allow merchants to funnel bitcoins from sales into payroll rather than dumping them on the market. For bitcoin to survive it must become more than a token purchase system.