sanscript: :-)
See, telling him/her what you mean then and there
usually is a god thing, instead of holding it. But that also depends on what kind of person you are...
tinyE: I'm not so sure. You never once screamed "Fuck you!" at someone and then a short time later realized it may have been a silly thing to do? Also, even if you have something good to throw back you may need to pause and consider if the person will get the point of the comment or it will fly over their head and just confuse them even more. In those insances "holding it" can be very usefull and prevent further bickering.
Depends...
You may not believe me but, no, haven't in a long time now. I don't use those words directed at someone. If I did that goes more back on me. In RL that is, because even I get more aggressive if someone yells/screams at me. (absolutely hate it)
I'm usually "holding it" (ironically) but still it does feel better to vent it, some of it at least. However, when I do vent it out, the valve is mostly set on moderate / non-insulting. (again, depends on the person listening :-)).
Nevertheless, there's no reason not to - as long as there is some progress, and it doesn't include meaningless words like Fuch U!, bitch!, ect... If the person doesn't get it... well, you've tried and then moving on.
Not talking about verbally hammering that person, even I can get "thick-headed". :D