CBR I am glad it turned out ok for you in the end. I can tell by your posts that you are a relaxed person, and with training behind you, all the better.
Speaking generally here, what would make me wary of drawing a firearm, or knife in this situation is the unpredicatbility that it can cause in the other person. As a martial artist of many years, I have learnt that it can often be the ones that don't train who can sometimes be the hardest to predict, as they often move in very random and unpredicatble ways (part of the reason why Bruce developed JKD - free plug haha) So after reading my waffle for the last paragraph, what I mean is that as a relaxed and trained person, who had full composure, and control of the situation, it could have gone one of two ways;
They could have done as they did and surrendered
They could have pulled a gun and shot at you, possibly harming you.
The second scenario would have been beyond the control of anyone, and in fact although you were trained and compsosed, in drawing the gun, you have created a less than favourable situation.
This post is by no means a statement against the actions that you did CBR, and in fact I admire your actions, as it is true that training can help combat theft - with power comes responsibility. My post does however raise the concerns that I have when faced with someone in the street who is adversely affecting my interests. For instance, I would have no problem in defending myself against multiple attackers, yet, if I do, I am playing a game of probabilities that one of them doesn't have a firearm or a knife, because that kind of thing can rapidly change the odds to go against you.