I've never had a single person shoot me point blank after I surrendered them.
I expect it every time I do it, (even wear a cup...) but no problems in all the years I have been doing it. Usually if it is my friends, I will just put one in them before tagging them, as I HATE it when I get surrendered... I'd rather be shot.
Here are some that I have on video over the years. The Reaper woodsball paintball guy cries, four barrel tags in one game junkeez - YouTube
yes, it was my first time playing there, and it was so target rich, I ran out of paint...
Here is a game from this past April, my first scenario. I surrendered quite a few. (one did shoot me in the back when I was about 50 feet away... Guess he figured he wasn't "really" out once barrel tagged. lol General Barrel Tagged! Paintball Country Assassin's Style Play Transformers Scenario ZoomCam - YouTube
Sneaking up and surrendering has its place, especially if you are way behind enemy lines, and shooting will only alert the entire base of your presence. Where barrel tagging is quiet, and effective for multiple "assassins creed style" kills.