Fibre optic interfaces NIC's allow for cable distances of greater then copper NIC's. But if you’re looking to compare speeds between Fibre Channel vs Ethernet the review this article below. Also there is alot of information on this from the internet.
Hi Tom can I please confirm that with open-e iscsi R3 enterprise I can use opticfibre cards in the open-e server and also the client computer and still make iscsi connections providing we use the cards that you support