I use one as a precision Z-axis depth gauge on my mill. As such I have to have the freedom to move both up and down and the DI needs to start in about the middle of its range. Hence the idea of a quick way to preset it to mid-range. The arrangement I use is a bit different from what I described but the idea is the same.

One advantage of using a DI in this role is the fact that they have virtually zero backlash due to the spring-loading of the internal gear mechanism.