You really dished out in that roll. I've seen that mistake kill several pilots. Good thing you are in such a forgiving airplane. Same mistake in, say, a T-6 at that altitude = dead pilot and passengers.
In aerodynamic theory, the R1 should have slightly improved handling characteristics. The airframe was designed around the heavier P&W R-1340. The lighter R-985 in the R2 made the plane a bit more difficult to keep in the Center of Gravity envelope and resulting in an aircraft somewhat more pit...
Good video. May I suggest you remake it on a light colored surface so the gun shows up better! :)