You gave me a few nice suggestions when I started doing film in dim light, Aguilever. Places I shoot are almost exactly the same settings. HP5 at 800 actually looks better than at 400 to my eye, and I never have a problem with it at 1600, so I use it a lot. I seem to always be around 2.8 with cheap lights. 1/30. A good spot might buy me a stop.
And, even on a brightly lit stage, I had exposure issues with a modern digital camera and wonky light. Shots would blow out the skin on the performers because of the weird colored backlights. Digital I tend to bracket and get a look, which invloves some annoying chimping and is too spray and pray for film. But once I get it I go manual unless something changes. For film I test with the meter to see if it's about what I thought, set it on manual, and forget about it. If there's a spot coming on and off I might compensate a stop with aperture, but in general HP5 seems gentler on highlights than digital.
It's just the way it works. Sometimes auto does it all right, sometimes manual does it all right and eliminates guess work. Use the tool for the situation.
Last time I shot was at a brewery, I sat at a tall table in the back of the room where people ignore me and I was shooting with a VR zoom on the F6 and when I pulled another roll out of the bag while it was rewinding the girl at the next table asked "You shooting film?"
I said yes, and she pulled a point and shoot out of her bag to show me. We talked about my settings and the film a bit as she wanted to try it with her SLR, too.
5 years ago, at the same place, even having a DSLR instead of a cell phone was weird, but now I'm not alone with the film.
