This is an upstream bug in FreeBSD, I'm afraid. The new Intel Atoms with the PowerVR graphics have major graphics compatibility issues with FreeBSD, and with Windows for that matter. They only seem to be really well supported on Linux. I'm using a D2700 board with 2.1-development in a live install. I'm using the i386 build, which one can, as you note, manage to install. I suppose if you memorize all your answers, 64-bit could install but I didn't see it as having enough benefit to be worth the headache.
Realize that with these boards, you have to use 32-bit Windows 7 due to there being no graphics driver support for 64-bit; and that some of these boards have 64-bit support disabled in the BIOS (for obvious reason). This is a 32.5-bit chipset (a not-real term I just made up to poke fun at this chipset). The processor is 64-bit, but unless you use Linux, you can't get working graphics in 64-bit. In 2011 (when this chipset came out), that's absolutely ridiculous. More importantly, the fact FreeBSD's console video doesn't even work (again it's hard to describe if you haven't seen it) and has glitches even in 32-bit mode, indicates severe underlying compatibility issues with the PowerVR chipset.
Oddly, Linux (even 64-bit) console video works fine, but that's with the latest Ubuntu that I believe uses a higher graphics mode. Even more odd, FreeDOS also works fine, without any of the missing characters. I'm no expert, but my understanding is that basic console video between FreeBSD and FreeDOS should be the same darn thing. Still, I wouldn't begin to blame FreeBSD and definitely not pfSense. This is an upstream bug that seems to be related to something severely broken in this chipset. Sorry Intel, but this is a fail.
If it helps you any, once installed on a D2700, 32-bit 2.1 snapshots have been rock solid (2.1 needed for Realtek drivers on the board I'm using), though sadly 2.1 is far from feature complete (VLANs don't work with traffic shaping yet, which I consider a pretty key feature).