My recent acting stint taught me that I absolutely detest being called "sarge". I would much rather be called by my first name/nickname, though maybe it's simply because it was a bit 'new' for me.
Personally (when in PC mode) I call most sergeants by their first name unless I don't know/like them, most inspectors/chief inspectors get called "boss" (though I do call some inspectors by their first name when the situation allows) and anyone more senior is sir/ma'am. We seem to have quite a relaxed approach in my force, though everyone uses the 'correct' terminology when appropriate.
There's a fair few middle management I've met who want you to refer to them by first name, citing the same reasons. I think it's signs of organisational change more than anything. I used to do temp office work for a big food company in my area who supply many large retailers and who also have a large local agricultural operation. Now when it was a standalone company, the people who ran it were old school landed gentry with the local peasants as labour. Lots of old timers there said it was expected to refer to "Mr Jones, Mr Smith etc...", as if the feudal system had never passed! When a big American company took them over in the 1980s, they swept this old management structure away and insisted
on everyone, from top to bottom, being referred to by their first name. Not saying this is right or wrong, but it is explanatory.
I too refer to inspectors and chief inspectors as "boss" in both special and staff roles. Mind you, I've also noticed a lot of police staff will refer to police officers of any rank by their names.