Hi Brian,
I don't think that there is an official statement, other than "not supported".
But thinking about the logic, I doubt that it will work:
Catalyst 3.4.2 is especially designed to work with the new ActiveMQ service, running as a separate process.
There is nothing like that in SOI 4.0.
Thus, my recommendation is to stick to 3.4.1.
MichaelBoehm