I think it has just as much potential to cause a rise in price.  For example, lets say someone usually cashes out all of his bitcoins that he receives from the pool everyday.  Then that person decides he wants a gold coin so he sets his account to pay out gold.  He's now saving up bitcoins until he has enough for the coin.  Could you imagine if every miner on slush's pool suddenly started saving up 600+ bitcoins?  That would be very bullish for the bitcoin price.