Just read thru this PDF on ubnt.com and noticed something interesting:
http://www.ubnt.com/downloads/XR2_Surge.pdf
All the competitor cards tested failed the RF Surge testing in the 5-6 kV range.
It is important to note that +6kV discharge is a realtively small value – for example human ESD contact is rated to +/-4kV and weather induced discharge can often be much higher.
I wonder how many peoples cards are deaf because of improper ESD. Take it out of the anti-static bag while talking with a friend and shock it deaf.