pfSense

did you submit a crash report? If so, what are the first two octets of your IP? (that's enough for me to find it, not enough for anyone else to know what your IP is)

108.28 (Sorry for the [super] late reply)

not seeing a crash report from anything on those first two octets. One in the same big Verizon block but well off from that, was about 36 hours after this was submitted, and looks much diff from what I'd expect here (contains nothing about wireless).

How is your wireless card configured?

I have the same wireless chipset in my system, too. My pfsense was upgraded to the latest version 2.2.2 and the stability issues are still present. One of the suggestions from Adrian Chadd would be to add the variable: sysctl dev.ath.0.hal.force_full_reset=1. It must be added in System-> Advanced-> System Tunables to last this setting even after a system reboot. I can say after that the stability of the wireless network become much better (you will still receive a few "stuck beacons" but not that much like before).

So I suggest to upgrade pfsense to the latest 2.2.2 starting now, and add the variable to the system!
Please someone remind to Adrian to consider this fix in freebsd-head.