2) Felons existed at the time the Bill of Rights was ratified.
That is true, but "felony" did not mean the same thing.
All felonies in those days were capital offenses. The list of them was short, such as burglary, robbery, murder, and rape. Today, in Indiana, theft--of anything--regardless of its value, is a felony. The problem with making "felony" the dividing line is that the state gets to decide what a "felony" is, and that definition is DRASTICALLY broader than it was in 1787.
Furthermore, there would be no need for a discussion as to whether "felons" could bear arms, because those convicted of felonies would be dead. The rest of us would be free.
Therefore, any discussion about felonies and the 2A needs to consider this point. And they often don't, because people think "felony" means the same thing in 2012 as it did in 1787 or even 1600. It doesn't!
If you don't believe me, read some old British cases. I once wrote a paper on one from the 1600s. The defendant was convicted of both robbery and murder. It turned out that there wasn't any evidence of the murder charge, so that was overturned. It didn't matter though, because the punishment was the same for the robbery--hanging. And that's the punishment he received.