If you go with the small drives, verify your pool is using an ashift of 12 before putting data on it.
Can you elaborate?
@Robert Trevellyan well maybe. Hovewer i've read a lot of discussions about and there is really no clear-cut proof that consumer drives are worse. I don't want to start another discussion here but it looks like it depends a lot on luck. I've read threads where people were cursing their WD RED's while others said these are the best HD. I will test my luck here. If they die quicky i will know i made a mistake :D