This may be perceived as self-serving, but remember that you asked, John!
Based on our personal experience, SpotterRF ground-based radar has made a profound difference in IPVS-related sales here at NMS Security. We are a distributor for SpotterRF; we also offer an optional plugin for Milestone XProtect, allowing radar-generated movement trails to be viewed, recorded, and handled exactly like a camera feed. In fact, our plugin received an award at last week's Milestone MIPS conference.
Why is SpotterRF hot? Verticals with very large areas of land where human, drone, or animal detection is required do not have any other cost-effective tool to cover more than a perimeter. At a list price of $6k to $45k, each IP-networked solid state panel can cover from 1 to 260 acres and 30 simultaneous moving objects. The system will direct multiple PTZs to view the moving object(s). Sophisticated filtering can include or exclude objects based on unlimited custom-drawn zones with size, direction, speed, displacement, duration, total distance (and more) dictating whether an alert is sent.
Check out http://www.nerc.com/pa/Stand/Reliability%20Standards/CIP-014-1.pdf for a mandated directive for electrical substations to improve their physical security. Airports, water utilities, data centers, mines, bridges, and any drone detection requirements are other especially strong verticals.
Locating, installing, and supporting a radar solution is very similar to IPVS. A three-day course and three installations are the pre-reqs of certification. Typical sales range from $75k to $__M.
We encourage any integrator to go to www.spotterrf.com and contact me if they would like more information on how to get started.