I agree that updating the hardware guidance would be pretty helpful. Otherwise, users would have to sift through the forums where there may be conflicting opinions.
The Atom CPU I mentioned before is this one:
Intel Atom C2750 Intel ARK Link
It's a 2.4GHz octa-core CPU @ 20W TDP which supports hardware AES, VT-x, and 64GB ECC
Here's an interesting board that is about to be released which uses the CPU:
Supermicro A1SAi-2750F Supermicro Link
Unfortunately it doesn't have a mSATA slot, but it has an onboard USB header that you could install a Flash DOM/Flash drive on. My only concern is it uses the Marvell 88E1543 chipset which I can't find any concrete info for pfSense 2.1 support, though previous similar Marvell LAN chipsets apparently had had problems with 2.0.x.
For the i3, I saw the i3-4330T:
Intel i3-4330T Intel ARK Link
It's a 3.0Ghz dual-core with HyperThreading CPU @ 35W TDP which supports hardware AES, VT-x, and 32GB ECC
There don't seem to be many interesting LGA 1150 mITX boards, and I couldn't find any by Supermicro or ASUS. I did find a few from ASRock and Jetway though:
ASRock IMB-181-D ASRock Link
ASRock IMB-182 ASRock Link
Jetway NF9J-Q87 Jetway Link
Both have some niceties, such as the mSATA slots (but no USB header for Flash DOMs). The bad points I guess is much less total RAM capacity support (16GB), no ECC option, and only dual LAN based on the Intel i210 + Intel i217LM for ASRock and the Intel i211AT + Intel i217LM for Jetway.
The perfect scenario would be either the Atom or i3 in mITX form factor, but also have 4 NICs either built in, or through a daughterboard like my current Jetway Atom D525 board. I think I can cope with 3 NICs at the minimum. Normally I'd say "screw this" and just use a separate 2-4 port Intel NIC on PCIe, but then that forces me to use bigger cases. I'd like to use as small as a case as possible since it's nice to have a small mITX sized "appliance" instead of a bigger cube box or a 1U rack (if I went rack I'd just use a mATX board anyways).
Edit: here's a review by ServeTheHome for the Intel Atom C2750 on the Supermicro board: ServeTheHome Review. Apparently the new Atoms are based on a "new" OOO architecture that is much more efficient and puts it basically on-part with the lower clocked i3's in multi-threaded applications. The older Atoms like the D525 are based on an in-order architecture which was pretty slow.