I really dont know how much the bottle pressure of a gun affects the accuracy/harmonics/operations of a gun, when used in normal operational parameters.
However, it seems to me that if you hunt, or shoot untethered a reasonable amount of time, you would want to set the inline regulator pressure higher than you might need to if you only shoot tethered from the bench.
I can fill my guns to 250bar max so after hours of research, and thousands of hours of super computer analysis (ie:random wildass guess, and where the gauge was positioned) I set the inline reg to 200ish bar.
That way when I'm untethered I wont be shooting with a significantly different pressure than I usually practice with.
If I'm honest I suspect it makes little difference for the way I hunt, or shoot, and I am making an effort to avoid getting too far down these rabbit holes that I used to obsess over.
I bought the Huma gizmo because I hate having to stop shooting to air up my gun. The only other thing I really need is a mag that holds a whole tin of pellets, and is of course self loading.