I think it’s possible to get yourself to respond differently than thought-fogging anger, to a given situation.
This may be true.
Concerning your focus on a productive conversation between individuals, I think it’s worth mentioning that responding here on OO.com isn’t always for the benefit of the person to whom you’re addressing. A member may want to just work out the ideas himself, or maybe he wants to respond for the benefit of a general audience who will read the thread in its entirety at a later date. Maybe he hopes to illicit better responses from more knowledgable users. Etc.
It’s certainly true that a person’s motives for engaging in discussion here (as elsewhere) may be multifaceted. One potential motive that you didn’t mention, but I believe that there are also some people who just enjoy getting a rise out of others, or who argue for the sake of sport, and don’t mind distorting truth or insulting or directing their argument to the posters (as opposed to the ideas), if they think it scores them “points.” While you and I may care about sincerity and respect, surely not everybody does. It’s a wide world and there are many types of people out there. Many types of people here.
But I do believe that the skills of tact/diplomacy, or even basic politeness, are beneficial for a range of conversational interests, including several that you mention. Or at the very least, I don’t think that civility detracts from them. They do perhaps limit the range of endeavors for some, however, depending on their motive.
That said, I continue to believe that those who are interested in these “productive discussions,” including using conversation to help one’s self (and others) come to the truth of (sometimes difficult) matters, and to better the world through persuasion, are best served by considering these issues and trying to engage one another with tact.
Also, understanding how to respond tactfully on the internet is sometimes delayed at best (ie. harder to discover the type of person you’re talking to), or even impossible. Maybe a member just doesn’t care to make so many blind guesses about the disposition of the person to whom he’s responding.
I agree – it can be difficult to know the character of the people with whom you converse. And whatever else is true about it, “being diplomatic” is a skill set, and even those who are earnest in trying to remain tactful will not always succeed. Despite best efforts, not every conversation will be productive. But if it’s the case that there are certain ways of communicating which are more effective than others, it may be in people’s interest to learn those ways and attempt to make use of them, insofar as they are able.
This seems to be the way of the world: many pursuits are difficult, but worthwhile for those who are interested in their benefits, and who stand to profit by them.
And since we know that you’re easy to anger, we might keep that in mind before posting a reply that might be construed by you as insulting.
Oh, people should respond to me as they see fit! 
I don’t argue for tact because I don’t want my feelings to be hurt – I can take care of myself – though my personal experiences certainly have helped me to shape and inform my views, which is why I share them. I think that people who otherwise wouldn’t care about how they present their views or how they interact with others (so long as they’re “on the right side” of a given argument), or those who intentionally provoke, need to understand why I believe some approaches are more effective than others, and that does include the observation that yes, when provoked, some people get angry. And this outcome does not often make for a fruitful conversation. N’est-ce pas?
But I argue for tact because I think it is a means by which not only Objectivism Online could be made a more pleasant and more effective forum for the discussing of ideas, but also by which Objectivists could more effectively impact society.
I believe that people who take these ideas seriously will do a better job of achieving their ends. Or what ought to be their ends, at least; trolls probably don’t stand to profit much through a call for diplomacy, and those who always must be right in every disagreement potentially stand to lose, as well. If fewer conversations result in flames, and if participants hold themselves to a code whereby they have to address themselves to the ideas, rather than allowing themselves to insult the “opposition” when frustrated, I think that conversations will more often result in one (or more) parties ultimately concluding that they were mistaken. Those among us who are sometimes mistaken might see that, or feel it at least, as a loss (and be mistaken in that as well).
Relevant to this discussion is the idea of “thick skin.” I’m sure much could be said about this, maybe a separate thread.
Having a thick skin is certainly valuable, and I do not mean to argue against it. We cannot control the actions of others, after all, and it is a wide world. But when we choose to interact with others, we can choose whether to be polite, whether to be tactful, whether to be diplomatic, whether to insult, whether to be rude, whether to be snarky, and so forth, depending on our ends, and what methods of communication we judge to best be suited for achieving those ends.
If I were discussing this with people who have conversations with substantial stakes – like, say, diplomats – I would continue to argue for diplomacy. You’re right that a thick skin would be vitally important in such a job, but so, too, would be tact. I would not expect (though maybe I’m wrong! 
) any response that tact isn’t important in diplomatic efforts, or that it is too difficult to achieve, or so on. We would simply try to assess how best to communicate our messages effectively, because so much is on the line.
However, I believe that the conversations we have on this forum have substantial stakes, as well. (Or potentially so, at least. Not every conversation is equal.) I believe that when it comes to philosophy – when it comes to ideas – there is a lot on the line. That there is everything on the line.
Maybe I’m more impatient than most, but I just don’t care all that much to tip-toe around strangers’ feelings, especially over the internet. What an exhausting job, with such an uncertain and minimal reward. This is the basic reason I’m lately leaning toward a “reasonable man” standard of discourse. If I think a reasonable man would be able to read through what I wrote and then respond decently, I think my job of tactfulness is done. The caveat would be if I really know and care about a person – then, the chance of my extra effort in tact paying off would be greater, with my greater knowledge of his or her person. In fact, you can see this happen a lot on the forum, as a language or cultural barrier is revealed – Anuj appears to be an example of this in this very thread! And since we know that you’re easy to anger, we might keep that in mind before posting a reply that might be construed by you as insulting.
Anyway, I was talking about ‘False’ pride. It quite rampant in the religious circles, you know. I hope it clearer now for you to make a refutation.