I have just found very interesting post on reddit about 8GB FC vs 10GB iSCSI.
Third I/O did an extensive test on 8GB FC vs 10GB iSCSI and the key findings were.
Third I/O found the efficiency of 8 Gb Fibre Channel to be higher than10 Gb iSCSI in the following areas: 3.9x greater bandwidth power efficiency 10x greater bandwidth CPU efficiency 3.2x greater database power efficiency 2.8x greater database CPU efficiency
Read entire report http://blog.erben.sk/wp-content/uploads/2015/03/ISCSI_FC_Comparison.pdf