PFSense. On this. Just downgraded to 2x4GB ECC 1333 DDR3 that I had lying around. Might want to use the 8 gig sticks for something else. But even now 10% RAM usage... so overkill status is still intact. :P
Also OpenWRT on a Linksys WRT1900AC as wifi AP. Might switch to DDWRT, will see...