While an officer, while in the line of duty, may be killed with his own gun (I think the number was 7 last year), you take the number of LEOs in the US today that OC (yes, I am talking about Homeland security too) that number is extremely small, like when compared to the number of people mugged in Chicago, WDC or NYC every day. And that "7" officers was the FBI number for the whole year 2010, and that was for the whole of the US...FBI statistics.
I personally have never been able to verify one incidence of an lawfully armed OC civilian being killed, by someone else, with his own weapon, in OR, WA or ID, ever. (these states I know, I'm pretty sure you can say the same about the whole US. The one case in WI several years ago has been debunked as a fairy tail, and the latest the guy was CC not OC)
With odds that slim, I would OC for the deterent effect. Much more provable argument. No, I was never fed the "Boggie man behind every door" lie when I was a kid...
How about the incident not long ago that started a nice flame war thread on here?