For over a dozen years, I logged over a hundred thousand miles per year flying on company basis on a positive-space basis (working in a technology capacity). However, although I was always flying on company business, on my airline, my positive-space status did NOT guarantee me a seat.

Deadheading crew and others essential to a flight (such as, say, a specialized mechanic flying out to fix a tough problem on a stranded plane) were given a "must-ride" designation, and were never subject to bumping.

I and others like me, however, were indeed subject to being removed from a flight in order to seat a revenue passenger. We did, however, have priority over any NRSA, and were in line to be upgraded to first class if any F seats were left after all eligible revenue passengers had been accommodated.