I know a little something about state constitutional RKBA and I can tell you that Gura made exactly the wrong argument– he started talking about how courts had interpreted these provisions 100 years later. Stevens was having none of this: he was allowed to make his point that it was 12-2 for a collective right in the early state constitutions. The correct argument was to put this in historical context: the citizens had just fought and won a revolution. Everybody was armed– what the state constitutions were saying was:”Hey, we will never disarm the militia like the British just did!” The English did something similar after they kicked James II out– they put a provision in their bill of rights guaranteeing an individual right for Protestants to have guns for personal protection. Stevens also made a big deal about this English bill of rights language showing that the english predecessor to the second amendment allowed parlimentary regulation of the right.
Gura could have neatly wrapped both these issues up together: The English Bill of Rights was adopted in the context of a revolution against a Catholic King who had disarmed the Protestants and ignored Parliament. The state bills of rights were adopted in the context of a revolution against an imperial power who had disarmed the militia.
Pennsy was an outlier because it was full of Quakers who were pacifists, and so they made the right one of self defense rather than military. Vermont had like 12 people in it when they became a state so they basically cribbed Pennsy’s constitution to save money. The Federal Bill of Rights was adopted in the context of nation-building: the convention toned down the states’ fire-breathing militia rhetoric in the first clause of the second amendment and then, in the second clause, reaffirmed the common law RKBA of individuals which was protected by the English bill of rights but, without making it explicity subject to congressional regulation.