EDIT: FYI, the C2758 can't route 10Gbe of traffic yet. It may be able to do close to that in a later version of pfSense once DPDK is done.
I consider to this statement or until the Intel QuickAssist will fully be integrated in pfSense.
Why not run 10.000base-T and get rid of the fiber unless you need the distance?
10 GBit/s are 10 GBit/s, eother over copper or fiber cable. And a new Netgear XS708e is starting at
around ~1.000 € its a bit high price only for changing the medium, or?
http://www.supermicro.nl/products/system/1U/5018/SYS-5018D-FN4T.cfm
If you buy from pfsense store, then its called the XG-1540.
This is starting at $1.250 in the USA or 1.500 € in Europe.
The C2758 wont route 10gbit/s in a mixed packet scenario.
I would also consider here but on the other hand nothing is more real then a real done test!
And an Intel 10 SFP+ Adapter is cheap to get over ebay for ~90 € bucks or so.
If the hardware must be bought it should be the XG-1540 as I see it also right
or a Intel Xeon E3-1286v3 and 16 GB ECC RAM, this would be also a really powerful
pfSense appliance that is able to handle this speed.