"be accurate, unlike many of the units I've used in the past."
Setting the bar a little high aren't we?
I'll second the Amprobe AT2005, old shop had an older AT2004, (It's littler brother) and it wasn't that bad. Also had another way old
Amprobe that could only be used live, and it was great for that. You really had to dial down the sensitivity, or it would ring through to other circuits, phases, other panels, next building... Once you got the hang of it, and how far you had to dial down, it would be fairly accurate, but that took years of experiance with it.
FYI Best way to accuratly
find a breaker, when you don't want to shut it down accidentaly in an office setting is an Amp Clamp and a circular saw. Open panel and have a buddy crank the saw over and off, while you run down the circuits. The one jumping up and down 7+ amps is your guy, start with phase first, then the breakers on that phase. You could use something quieter...
But it needs to have a good kick in the amps!