Very interesting tool rekd0514! Bookmarked and subscribed
I've built and used many PFSense routers on old IBM/Lenovo Thinkpad T series....you can pick up some cheap T-20 and T-40 series...and with the Thinkpad series you get good business grade standardized chipsets and onboard Intel NICs....PFSense runs great on them.
I also became a fan of using old laptops for this purpose....built in KVM, low power consumption, low noise, small footprint on your desk/counter, and built in battery backup.
I know you rather use an intel nic but what I did on my 2 pfsense laptop routers is get this product from trendnet.
I use the trendnet port to the WAN because I am going to get no where near the 1Gbps connection while I use the built in intel nic in my thinkpad to the LAN network. It's a lot less bulky than the solution you look like your going to try. And I believe you have an intel nic on the gateway as well.
And yes I know that the card bus is capped around 480mbps I believe and can't truly run at gbps speeds.
I completely agree with Stonecat on this one. Old Laptops are almost designed for this purpose.