I have no personal experience with the 3 and 4G radars.
Some say they are great...some say they are about equal to the average digital radar in OVERALL performance. The big difference is close aboard...less than 100 feet or so they really shine and maybe out to 300 or so feet thay have a tiny edge. Past that ,the same till you get out 15 miles or so for the 3G where regular radar seems better and the 4G is good but not better out to 30 or so.
Again...this is from trusted friends and other professional captains...and far from scientific. Best to play with one till you are sold on it...