it's now a little over two weeks since I've had all six of my Linptechs kept online via a daily change to the motion senstivity setting (change to low, then back to normal desired setting) via RM. Doing this instead of rebooting them weekly via smart plug.
So three of them are now at over six weeks w/out going offline, and the additional three I added to the test are now just over two weeks w/out going offline. Optimism is increasing... 
A little over 2 weeks later and everything is still running fine, Linptecs are not going off-line.
So that's three of them at just over two months staying online, and the other three just over 4 weeks staying online. 
Sadly, I'm back to report failure.
A somewhat odd failure. Starting around the time earlier today when I updated the C7 that the mmWave sensors are on to 2.5.0.159, the three sensors (the ones I added to the test part way through) stopped working...logs:
Update to 2.5.0.159:
The three mmWave devices stopped reporting motion right around the time of the update. (Motion Hall Bath, Motion Walk-in Closet, an Motion Master Bath.) Those devices still "talk" about being online, but don't report any motion.
I did reboot the hub w/a database rebuild, didn't help. The three that aren't reporting still aren't reporting. The other three are reporting normally, and all six of them are on the same hub they've always been (C7). All of them are on FW 1.05.
I'd roll-back to the previous build, but family is around/tripping automations and don't want to have to go through the "Don't panic, everyone, if nothing works for a few minutes" speech at the moment. 
Anyone have any thoughts about this?
Thoughts? Seemed to good to be true.
This approach (changing sensitivity daily) has worked for @csteele, so didn't seem like a bridge too far.
The way the second three failed just at the platform update, and that the other three have continued to be faultless, seems a bit odd. Can just be a coincidence, of course.
