Just to show that they are a YMMV, I have had great success dealing with jet.com, after spending $800 on about $1200 worth of computer hardware and having items in my possession within 5 business days after qualifies as a success.
Between my girlfriend and I, multiple addresses and debit cards - we got quite a few good discounts from "first" purchases.
For what it's worth - I'm leaning toward avoiding them now as within the last week I attempted to place an order worth $852 which was cancelled on its' own, and I had to go to my Financial institution to get funds reversed to reward a different e-store with my business.