I've always liked SOS. Had it as a kid, we called it dried beef gravy.
I don't know where you ate, but I can remember SOS at every Army mess hall I was ever at. I also got it sometime at Naval Air Stations.
I found some chow halls much better than others, but most were very good.
Can't believe you didn't like the PIRs. There were about half of the varieties I wouldn't eat, but the other half were good! Thus I made sure I had the ones I liked when we went to the boonies.
Sarge