Ortiz will have to decide what gives him better leverage accepting or declining arb. If he accepts, he is Sox property for 2012 at probably $14 million or more. This would give him leverage in a 2 year deal if he wants a reduced rate of 2/20 or something like that. I believe he can agree to a deal with the team prior to the arb hearing and it can be a multi-year deal.
If he declines arb, he can try to exert pressure using the offers in hand from other teams, but the Sox may not want him for the price, plus they get draft picks if he leaves. I think he has less leverage if he declines... much less.