I got an Insteon USB PLM working, much of what I learned is on this thread. Hard part was linking each device one by one.
Using USB PLM on Hassio on a raspberry PI3b, it has been very stable for about 3 weeks.
I just barely decided to pay the $5 a month for HA cloud service to get Alexa working. Working on moving off of the Insteon HUB that is handling all my Alexa integrations now.
The problem with having an Insteon HUB and PLLM via HA at the same time is that if the HUB controls a device the PLM never knows about it.