FreeBSD on Rasperi/Bananna-Pi for router?

[Ghost3d]

So I'm about to purchase a Rasberry/Bananna Pi device to upgrade some features in my network routing. The thing is I'm concerned because there is only one NIC [Gigabit]. I was thinking either pump traffic in and back out [assigning 2 ip's to that one nic] of or just make a virtual nic for traffic routing and point inward/outward traffic to its destination...
The Pi device is then plugged into the switch and wa-la.

Ok so my traffic peaks at about 10-12MB/s at the WAN side, my question is which setup would most likely give me the best performance [basically no reduction] for routing traffic? I'll be running pf, and wifi for an AP. I think the quad core arm with that Gb-nic is plenty of power, I'm just curious about the software setup being the bottle neck. It may not even put a dent in it but I thought I would get some opinions. If you have a totally different idea I'm up for hearing it.

Any hits would be greatly appreciated

Ghost