I would discount that study, Dog. The only negative about a higher mounting is the effect of vessel motion. In the case of the mounts concerned, they are gimballed.
If you are relying on radar at the short distances a blind spot might cover you are operating in a scary manner. The whole point of the unit in the first place is to be able to reach out, over the horizon, and detect objects before they are upon you. If you depending on radar for close in detection it is similar to the driver who is only looking down his hood to the road in front of him. By the time he see's it, he's hit it.
“Scientists are people who build the Brooklyn Bridge and then buy it.”
Wm. F. Buckley, Jr.