I was going by this summary that if you have only 1 of those, it should be okay. I do not have a second controller, but looks like a good investment for longer term.
Is the reverse possible? ie, use ST hub devices from Hubitat? Using ST hub as another external zwave controller.
With the sylvania bulbs, zooz zen25 double plugs benched, and the looming issues with Monoprice 4-1 sensor, I am considering using the ST hub for these problematic devices there. Otherwise, one of the external z-wave controllers. I just wanted to avoid using more than one hub.