I don't find the need to adjust the rear view mirror to night mode with the tint. I think so far there were only one time and I think the car behind me was using high beam.
This is subjective to personal wants/needs but IMO, yes, auto dimming or even tinted glass on rear view mirror is a nice to cut glare with tint up to 20%. Different if you are using limo tint or perhaps reflective tint.