I have done many FTF transactions. I ALWAYS choose the location. I have done a couple after dark, just because of schedule conflicts. I am always armed. I've had a disagreement here with someone about it (on another forum thread on this topic) but we sit in MY car. I do check under the seat after they are gone, to make sure they didn't drop anything illegal in the car.
But, I have control of my vehicle. I have no idea what might be hidden in theirs (weapons). Granted, they can have a gun on them, but I do watch their hands as well as I can.
If they have a 2nd person with them, I ask that the 2nd person remain in THEIR vehicle.
I've never had an issue. I have only refused the sale of a gun to 1 person... A Five Seven. Guy had a strong foreign accent, and he would not sign my bill of sale that stated he could legally own a firearm. He kept stating it was his "Obama insurance" and he didn't want a paper trail. But no bill of sale signature, and I do not sell the gun.
Typically, I try to mention that I have a bill of sale for both of us in my email correspondence. With this guy, I forgot. And, he is the ONLY guy who ever had issue with it. And, after it was over, there may have been some reason why he could not legally own a gun. Who knows. THAT was the only one that made me nervous after he flat out refused to sign it. It was after dark, and my radar went way up because I didn't want him to just take it or try to rob me...
Otherwise, all have been fine, and I have no problems with FTf sales. (and, I sold the Five Seven to someone else 2 weeks later)