[This could be a critical inflection point for online retail. If either company can make its offer work, free shipping could become the industry norm. But if the companies can't divine the sweet spot, and they end up losing money, this could be the last time we'll see any such offers -- except for very limited, one-time deals.] I don't think either of them knows if it's going to work out economically or not, ... The only way to know is to try. Ken Cassar