When I have been diving into the DFF-UHD vs using the onboard for a 1KW, it appears that the processing is different because it is done at the black box. I don't anticipate going deeper than 1000 ft. What I was reading is that the processing handled at the UHD will give better resolution and discrimination. The hope for me, would be out on the shelf in about 600' being able to discriminate between mud and gravel. Finding areas of rocky areas for Lings vs gravel for Halibut, and mud for wasting my time. My old Garmin XSV with a GT51M was useless at these depths. I only knew that I was not fishing any more when I could feel the pipe jig going into the mud as I pulled it out. I have some marks, but the reality is that I don't know why they produce and I feel a bit like some of that style of fishing has been random which which is what I want to fix.