Update- posting this for the benefit of those who may be searching for similar issue in the future.
994i/Polisy/eISY all have 1024 device/scene/folder limit. Not there- I am halfway.
Programs/program folders not a factor.
Insteon PLM link DB- also in mid-500s, not at ~950-1000 link limit (I've seen various limits)
However, Insteon has a 255 scene limit. I'm right against that limit.
So off to figure out how to partition my system between 2 IoX system and PLMs with one Polyglot and one Elk.
