Adding a Smartthings Hub as Primary with a GC3 as Secondary

I understand some of the benefits of adding a ST hub to a system as the primary Z-wave controller while using the GC3 with as the secondary. You essentially run two parallel networks that allow using devices not supported by ADC under the ST side of the network (zigbee for instance).

I have a stable system GC3 consisting of 4 takeoff modules (31 wired zones), three locks, two garage doors, some z-wave outlets and switches and soon to add irrigation control and water management (flood sensing/shutoff). I want to add a Smartthings hub so I can begin to play with scripts (ITTT) and other automation functions not available on ADC.

So I am somewhat familiar with the “pros” of doing this, but are there any “cons”? Does running a ST hub as primary detract at all from the portion(s) of the system that the GC3/ADC would otherwise control alone?

The ultimate con of the setup is the difficulty that can arise. There may be some isolated issues with some primary controllers passing incompatible device info to the control panel, then ADC showing malfunction on the incompatible device all the time, but largely there is no impact on what you have access to with ADC.

The impact is to troubleshooting. The primary controller should pass all newly added device info, but in some combinations of controllers this fails, and you then may need to remove the pairing of the controllers and re-link them.