I'm a CS PhD student, currently ABD. I have a 122 key Model M on my workstation in my office, and another on my home computer. When I'm not in one of those two places, I carry a Motion Computing tablet, with a HHKB hooked up to it.
I don't worry about my keyboard for 3 reasons: it's old enough that I get jokes about using a keyboard older than most of my students, there are 3 other Model Ms and a Filco in that office, and the door has access logs, so if it did get stolen, we'd know who in fairly short order. It's also the heaviest of the keyboards in the office, so the last to be grabbed, most likely.