Sorry for only getting back to this thread now.
By now only the rushes from the project are left, so the grabs are quite compressed.
The short I used them on was also more than one and a half years ago (feels like 3 with the pandemic), so I don't exactly remember my exact setup. Material was 7219 and lens was a 25mm Superspeed Mk3, shot at around 4-5.6 if my memory serves me right. Here's a link to a scene where I either overexposed by 2 Stops and used a BPM 1/8, or overexposed by 2/3s of a stop and didn't use a BPM.
As I can't find the camera report anymore, you'll have to guess what is what. -I know, I know, very scientific.
However, what you'll realize looking at the grabs, is that they don't look that different.
My take is, that if you want to have your diffusion stand out more on 16mm, it might make sense to favour stronger filters over what you are used to from digital, as 16mm is usually "softer" from the get go. If it doesn't need to have a highly diffused look, I think diffusion filters aren't that necessary.
Of course this depends on what material you use, what lens, what stop, how you expose and what kind of lighting is used...
These are just my feelings and thoughts, not scientificly proven at all, so if anybody feels I'm in the wrong, you are welcome to correct me!
Next year I'll do a camera test with some diffusions and report back.