Occasionally use the MBUS only, but usually it's a red dot. I have a swing out 3x magnifier so at 25 metre distances I'll use the RDS/mag and at 15/10 metres (the stipulated firing distances at my indoor club) just the RDS.
I suffer from astigmatism, so when I'm just on the RDS, I'll still flip up the rear MBUS to pin hole the dot through the sight aperture.
Other than basic target practice at 25m (at which I'll shoot groups), main shooting is a series of timed trials at mini-man targets from all three range distances, so the quick swing and flip up sights are ideal for this.