HP-8750 vs HP-B9180

Just saw the 8750 at Office Depot for $325 after rebate, valid until 6/17. Quite awhile ago, I had already decided to get this printer once it hit closeout prices. I am not in a hurry because I already have an HP Photosmart-all in one that uses the Vivera inks but of course it just can't do 13"x19". Well, now the price is right, but because of the B9180 I am having second thoughts. Sure the B9180 will cost a hefty $700 up front, but if you consider the 8750 consumable costs ($100 for a set of cartridges and the cost of HPPP paper) it seems like the B9180 would cost justify itself in relatively short order. Even when only used occassionally. Couple that with the durable pigment inks and expanded paper options the 8750 just doesn't seem as attractive anymore. What do you think?