I think part of the issue has to do with what one views in others as worthy of offering respect.

As a young LT I addressed my NCOs by rank and last name, in deferrence to their age and experience--each of them was older and wiser than I. I spoke to most of my (E-4s only had SP4s, no corporals) and below by their first names. Similarly to MikeF, when I addressed them by rank and last name, they knew they were in trouble. As I rose in rank and experience, I was more likely to address my junior NCOs by first name, unless they were in the comnpany of their subordinates. I never came to a point whre I could address an E9 as anything other than Sergeant Major X. Perhaps the weirdest event was coming to a position as a senior Major where I supervised my former PSG, now a GS-11. Calling him by his first name was always tough for me and calling him PSG L was inappropriate. Funny thing was that I had no problem addressing by first name a former section sergeant (also an E7 during my Plt Ldr days) who was also now a GS-11. It was also tough to address my former college professors as anything other than Professor X even though I was also a professor at the time.

BTW, I haver addressed anyone of any rank simply by his/her rank, except to be insulting. That practice is the epitome of depersonalization as far as I am concerned. It is probably more demeaning than referring to people just by last name.