The first one (the fun one) to think about is the legal shit-storm using a factor that nebulous would create.

Generally it is pretty easy to show the crime statistics of an area, especially if there are a high volume of arrests there.

That is, courts generally recognize the right of a citizen to engage in OC and to do so anonymously and without being subjected to any detention.

The court recognizing that will not protect you from a 911 call.

If we're going to burden that and Terry Stop and ID the OC, we damn well better have a really good answer for just how high the crime rate can be before we can strip the citizen of that right, otherwise the court is going to say we are eviscerating a right

That is again answered by crime statistics in the department.

The second one (less fun) is that a Terry Stop requires the Terry factors: Reasonable Articulable Particularized Suspicion of a Crime. In application, you see OC_Guy, who you've never seen before, in what you KNOW is a bad area walking down the sidewalk at 2 in the morning with a rifle slung. What crime do you have good reason to believe OC_Guy in particular is involved with?? I don't believe anyone has any good reason that they can articulate to say that OC_Guy particularly is involved in a crime. To the contrary, everything we've observed is perfectly legal.

A Terry Stop, may be had under Reasonable Suspicion as well! and that suspicion can be based off of innocuous facts, carrying a gun in itself is of no harm, same as walking the street in a HCA at 2am, but if you add those together "Caller states that there is an armed man walking down Hatcher St." The Officer will likely conclude that 1. It is very early 2. Hatcher St. is in the center of a HCA due to the fact that he will no this being it is in his district, and 3. The man has a weapon. Given those facts you can assume that the man could be in the process of some crime, but you must first question him to know if one has been or will be committed.