|Speaking for myself, Duncan, The Question is a double-edged sword.|
In a formal discussion group, I think it is great, which is why I added your article to the SOLO Clubs page as a link. The purpose of a SOLO discussion group is to engage in a truth-seeking dialogue. Your question brings the abstractions back to observable concretes -- good Objectivist epistemology.
Many other times, though, people who express opinions in a drawing room or wherever are not necessarily looking for an argument or a debate. They simply want to vent. Granted, they should be more careful with their tongues so as not to attract such aggravations in the first place. However, unless the setting is formally aimed at the goal of a truth-seeking debate, such distracting disagreements may only serve to annoy rather than to enlighten the person in question.
I will dissent a bit from the Rand-Branden-Peikoff canon by suggesting that it does not always serve us to say openly that we disagree with someone, especially when the disagreement is over a trifle. I might say, "Well, that's interesting," and leave it at that. Why? If I do express disagreement, the other party might just ask me to explain why. Unless I have loads of extra time and energy on my hands combined with a purpose in line with my other purposes of the interaction, such an effort will have a high probability of negative payoff.
For instance, I have a co-worker in the next cubicle who has openly stated, within earshot, that she would like to see all smoking outlawed. My purpose in working at NASA is to earn a good income while doing cool stuff related to space. Arguing with this woman about the evils of her fascist agenda falls outside the scope of that purpose. So unless she asks me directly, I see no value in raising a disagreement with her. Even if she does raise it with me, I will just tell her my opinion without trying to "explain" it to her in excruciating detail, since "explanations" just raise more resource-consuming objections and, more to the point, will ultimately not make any tangible increase in my personal liberty.
If I chose political activism rather than engineering as my core career and central life purpose, then I would naturally engage many more people in debate and would hone my skills at such.