Two things convinced me to have a box dedicated to pfsense (or whatever I end up using):
@monte 's earlier advice on the subject, and
The need for it to keep working during a lightning storm, during which I typically unplug any expensive or delicate machines but also during which I still want to maintain wifi internet access. Meaning: it could still get nuked by an electrical surge from a nearby lightning strike, but at least the replacement cost would be low. Hmmm... I suppose better still would be switching to some kind of completely wireless internet access during such storms, by maybe converting my cell phone into a hotspot or using a Verizon jetpack.... In that case, having the router be low power would be very nice indeed, because then it could run on batteries during the storm and thereby have no lightning risk at all.
Reporting back: I installed the Gen2 Emporia Vue, and it "just works" on the first try. Ironically, it reports the same amount of power for my refrigerator as the far less expensive TopGreener power module, so I guess the TopGreener is more accurate than what I had thought. At least the Emporia Vue's built in graphing is far superior and involves no switching, so overall I'm glad I made the upgrade.
@Martin_Smith Microwave backscatter can show rain out to some distance. At airports an optical method is used as it also covers fog and snow. It really comes down to why you want to measure distance in rainy days and what sort of distance you intend or need to cover.....
@Westie That feature can also be used with the Arduino Nano, or any other ATmega328P-based board.
I had NRF24 + RFM69 running for a couple of days using a Nano as an Ethernet MQTT gateway and it worked fine as far as I remember.