Range Finder options for landing improvement

Now that the LIDAR-Lites are not available, that leaves the fairly expensive Lightware sensors or this Teraranger or the older max botix, however, both have much more limited range (14m and 7-10m respectively).

How well do the less expensive options work for improving landing and for reverse thrust landings? Is 14 or 7m enough to improve the landing of a plane and if so, how reliable are these sensors?