That's just comparing individual chips though. Comparing the more important ratio, hashes per dollar:

BitFury 400G: 400GH/s for $8000 = 50.0 MH/s per dollar (Rasp Pi included in price)
Drillbit Board: 16GH/s for $300 = 53.3 MH/s per dollar (plus the cost of the host computer)

So not that different really. Plus you don't have to fork out a whopping $8k straight away. The power efficiency of the 400GH/s rig is also a bit lower than the Drillbit boards, moreso when you compare using the more power efficient stock 2GH/s rating of the Bitfury chips, rather than 2.7GH/s.