Interesting that the answer to my question seems to be don't mess with these things and they don't work reliably.  i am running these on 2 separate powered usb hubs and they work just fine and have been very stable.  it seems like the problems start when cranking them up too high and when using inadequately powered hubs.  I don't have that problem.  I do understand the response that running them with separate workers/devices does not really accomplish anything and isn't worth the bother.   Thanks.