Presently, changing the value of the search radius options from within a design that uses inch units results in the values being divided by 25.4 when the defaults are saved. Changing other defaults when the design is open in later sessions results in further divisions by 15.4. This spirals into a totally useless search radius very quickly. The natural thing to do is to reset the radii when this is seen, starting the same spiral over.
This does not happen when the radius options are changed without an open design.
According to the programming staff (as reported by customer service), this is working as designed and no corrective action is needed in the software. I hope that this "feature" was just an oversight rather an intentionally created. The recommendation was to submit it as a new idea, so here it is:
If the defaults are changed while in a design, do not convert the units so that they stay the same. Instead of having text on the screen that says "Radius dimensitons are shown in screen units that do not depend on sheet units and the zoom factor", mention that they are based on metric units modified by a zoom factor.