The disadvantage of using Bitfury chips is the low "GH density".   PCB size = 12cm x 12cm ?  If boards are spaced 1cm apart = 144cm3.  42 GH per board.  0.29 GH/cm3 or 3.4 CC/GH.   Fluorinert runs about $0.80 per CC ($80 per Liter), thus at 3.4 CC of fluid per GH the fluid cost is $2.72 per GH which is pretty high.  The higher the GH density the less fluid needed per unit of hashpower and the more economical the system.  My goal would be to get fluid costs to <$0.25 per GH and full system cost (excluding SHA-2 boards) <$0.50 per GH.