The bond strip in AC cable is NOT an equipment grounding conductor! It is simpally an add-on to reduce the impedance of the armor sheath when the armor functions as an EGC. It does this by running along the underside of the armor and has casual contact with it. Old AC cable (pre '60's) did not typically have it and the impedance was very unpredictable, particularly as the cable aged and corrosion occured. Even with the bond strip, the impedance of the armor can grow to an unacceptable level on long runs and those with numerous terminations. Hence the benefit of MC and AC with a separate EGC. I know of not requirement to terminate the bond in any particular manner although I was always taught to back-wrap it under the clamp. That becomessomewhat of a moot point with some of the newer push-on connectors.
Both metallic and nonmetallic wiring methods have pros and cons. AC and MC are not immune to punch thru and I have seen more than one sheet rock screw perfectly run-thru aluminum armor. I would consider corrosion and poorly made terminations the biggest problems for armor because it attacks the EGC, a problem that can be avoided with MC or AC with a seperate EGC. Even locations that are originally 'dry' can become wet enough over the life of the installation to cause deteriation of the armor.
