While I'm not as well-read legally as many others here, it seems to me that simple common-sense should answer this question adequately. To my mind, the primary goal of people using a gun for self-defense should be to minimize the risk of harm to themselves and their loved ones. To this end, I think that engaging in unnecessary confrontation is detrimental to this goal and thus should be avoided.
Where things become a bit murky is at what point, exactly, that you cross the line from minimizing risk to unnecessary confrontation. For example, if I were to find an intruder in my home, I think it would be perfectly reasonable to command said intruder, at gunpoint, to get on the floor and place his hands behind his head as such a position would minimize his ability to harm me or my family. Whether or not holding an intruder in such a position until the police arrive would constitute a citizen's arrest I cannot say, but it seems to be a prudent and reasonable course of action to me.
What is not so clear-cut, however, is the appropriate course of action if the intruder does not comply with such a command. Personally, if the intruder does not comply but is obviously trying to leave my home without harming me or my family, I will not attempt to impede his escape as that would cross the line into unnecessary confrontation. If, however, the intruder does not comply and is not obviously trying to leave without harming me or my family, then he represents a threat to my safety and that of my family and he may very well suffer the most dire consequences for his actions.
What I absolutely would not do, however, is physically confront someone who does not pose an imminent threat to me or my loved ones. For example, I would not leave my home to confront someone attempting to steal a vehicle from my driveway. At most, I may shout at said person to vacate the premises as I have called the police whilst remaining in the safety of my house. More likely, however, is that I would simply attempt to get a good enough look at the thief to provide a thorough description to the police when they arrive.
He convinced the perp to go with him to the police station nearby. 
Now this may be a surprise to many, but generally the police are not at the station, the job requires them to be on the street... So the office staff there actually had to call for an officer to return to the station! And yes, it is a true story, I showed up after it happened and the employees were still still talking about it, and the owner and I discussed it. 