I have been experimenting with very low BUIS on my RDS-equipped handguns. This setup uses a rear sight with notch just visible at the bottom of the window, and a shorter-than-normal front sight, which shifts the POI up into the center of the optic window.
The POA remains the same regardless of whether the dot is on. The index is the same with dot and BUIS.
Not surprisingly, I've had numerous questions about this setup--first and foremost whether I can hit anything with the dot off. See below. Low Witness works really well and I recommend giving it a try. If you have a Glock, the switch is especially easy. All that's required is a front sight that's about 0.050" shorter.