Sounds like a good move. I don't think you would ever get that working as you wanted originally. You would need a switch that is able to talk FC but also extract the IP from IPoFC. Does such a switch exist?
It looks as though the IPoFC protocol was put in place to allow high bandwidth between servers that are already on a FC network and not as a bridge between FC and Ethernet.
If you were using pfSense to bridge 10Gbe interfaces then the limiting factor would be in software not the PCI-E bus. The bandwidth of PCIe varies by how many lanes what generation etc but say a x8 card in a v2 slot could, theoretically, support 32Gbps. However the limit in pfSense is, I believe, currently around 4Gbps. This is due to a single giant locked process coupled with a the maximum single core speed of current cpus.
That is my limited understanding but I could easily be wrong! ::)
Steve