For helos, getting slower at the MAP is critical to lower mins. Remember that airplanes land, then stop while helos must stop, then land! For an airplane, the MAP can be 2 miles from where it finally stops.
The real issue for low minimums to heliports is not the DH, it is the distance from the missed approach point to the touchdown point. This distance is determined by the speed of the helo at the MAP, since only so much decel is comfortable for the visual section of the approach. The speed at the MAP is not significant for airports, since the runway length is all available to let you come to a stop.
For a typical helo at 70 knots, it might take 1/2 mile to stop, so the vis could possibly get no lower than that. The vis affects the DH, too, because if you work up the natural descent angle of 3 degrees, the DH could be above 130 feet.
So we are working on how to get much slower while in IMC so that when you break out, you can just put the helo down. There are two ways to do this, either make the helo able to do it automatically, or beef up the pilot's cues so that he can handle the machine as if it were in visual conditions.