Jack, that was a pretty good post, and I largely agree with you.
I would, however, point out that although hygrothermographs
satisfy the decision rule of Occam's Razor ("Exchew
complexity," aka "K.I.S.S."), they are not absolutely
"bulletproof." We have found that their Achilles' Heel is the
clock-work drive mechanism . . .which has recently crashed, at
one time or another, half of our instruments. Yes, of course,
they are available battery-powered, and I have no experience
with those. Subject to the reliability limitations of
low-voltage fractional-voltage motors (and batteries and those
who monitor them) this might answer the problem.

Henry Grunder
Conservation/Preservation Coordinator
The Library of Virginia