I thank you all for your feedback.
Ideally, what I want is a single interface for my less-tech-savvy users to watch video programs, regardless of the origin. Plex does a lot of things well (including locally stored content), and their DVR feature is [slowly] getting there, but it doesn't have the TV Everywhere piece. Channels Plus has the DVR and the TV Everywhere piece, but not the local content. They both have two-thirds of the wonderful video server application that I'm looking for. They have their own clients, each with its own interface, need two different server installs (the least of the issues) and both have an ongoing fee.
Was I not already invested in time and funds in the Plex universe, and was using the HDHomeRun DVR (or no DVR at all), moving to Channels Plus for $80/year would seem like a bargain. But I am Plex-invested, and have a Video provider subscription which includes a DVR... but there are times I need either more tuners, more capacity or more flexibility (like when I was away from home and wanted to watch the hometown news; can't watch the locals on a TV or from the DVR using the provider's software).
Anyway, thanks again all. I'll keep my eye over here to see if Channels Plus' value proposition gets to the point I can take a serious look-see.