Well, since nobody has replied...
It is my understanding that this chaps earlier product, the Trimetric, was basically standard fare for off-grid systems. I've been in about a half-dozen off-grid houses and they almost all had a Trimetric on the wall.
The Pentametric is his new-and-improved product and only became available as of about a year ago. Depending on your system, the Trimetric might be all you need, and it's cheaper.