Mig3, that's another incident. I am talking about the reason you have to deselect approach after becoming visual before disconnecting the AP, as per the airbus OEB. (too lazy to look up the number, if it rings a bell, you know what I am referring to)
Zoneair, did you ever hear of the DC10 crew that thought it pretty harmless to pull a CB for some engine indicator at cruising altitude? They blew up an engine in the proces, tearing a hole in the fuselage, killing a passenger. I'm not saying arming approach will have that effect in the cruise, but you just don't know for sure whatever undiscovered glitch you might encounter. Cruise level is not the place to experiment if you ask me.