STW, you do realise that you are not employed as a “solely “ freighter/cargo pilot? Comparison with the other cargo carriers is invalid. You are actually enjoying pax rates to fly the 747 freighter, as we no longer have the pax version. Likewise that is why your contract doesn’t change when you transfer to the Airbus/777 fleets.
An Operational day is not a day off on your published roster as you cannot Guarantee the day off and hence plan to be somewhere or do something you desire. Should you not be abused on your O day then yes, you can treat it as a day off in retrospect, but what use is that if you couldn’t Guarantee its use?