I just ordered a Drobo (1st gen) and will need to be getting some drives for it. I don't need a lot of space and can't afford too much after paying for the Drobo, so I am thinking 3 500GB drives for now; I can always expand later, and 3 500GB drives gives me more space now than 2 750GB drives for around the same price. I have been concerned with the (seemingly) high defect rate for the new larger drives, esp. Seagates, so that is another reason for using smaller drives. Does buffer size make much difference in this application? I am thinking not, but any advice would be welcome.