Hello, a FreeNAS newbie here...
I just registered to let you know that I just received a X10SLM-F + E3-1230LV3. I just started testing with ESXi 5.1 and a virtualized FreeNAS 9.1.1 with a M1015 in passthrough (flashed in IR mode).
So far, everything is working in ESXi. Had to install VIBs for i210 and i217 NICs, and updated IPMI for proper health monitoring under ESXi. The E3-1230LV3 is amazing. It just sips power (25W TDP, 8 threads). I paired it with a Thermaltake Macho for passive cooling an even under heavy burn in load, it stays cold to the touch.
I will be testing with native FreeNAS (for contingency) during the following days. I'll let you know about NICs and USB 3.0 then.
If I where you, I'll stick with a Haswell board just for future proofing.
N.