I don't, but not because I think my neighborhood is incapable of producing a violent pt. Given the likelihood of the event happening on one of the two hundred or so calls I run a year, where a violent pt gets past a LEO safety check and I am injured, its just gonna be 'one of those things'. I think I stand a higher risk of getting hit by a car on a scene, hit by a car crossing the street off duty, or developing a non-work related health condition that could take my life.
I do what I can to migiate any of it happening. I do wear PPE, because its pretty easy to do and can mimize the chance of my being infected by a pt. But, to start every call with the donning of body armor, going into each call with the first thought being, "This patient might hurt me" is not a mindset I'm willing to put on.
I've been in a few edgy situations where the sphincter factor was a bit high, but they have resolved well. If I end up paying a price for this attitude... well... that sucks but none of us get out of here alive. It's a risk, I agree, but to me an acceptable risk. I don't believe the vest would give me a sense of protection, and I would be concerned that it may lead to a feeling of invulnerability that may lead to less caution practiced on scene, because.. "Hey, I'm protected, I have a vest!"
I think its a personal decision based on what makes you comfortable, much like the Yes or No debate on gloves on the other forum. We take risks we feel are in the 'acceptable' column which is often determined by a purely subjective standard.