I have both the ST hub and the Phillips Hue hub. For whatever reason ive only added my bedroom and spare room bulbs to the Phillips hue hub ( then added it to the ST hub ) and my office bulb is only in the ST hub, i cant see it in the Philips Hue hub anywhere. Now in all three rooms i use the Hue dimmer switch to control though ( as well as motion sensor automations in ST.
Is it beneficial to readd the office bulb into the Phillips Hue hub incase of any ST or internet outages as i believe the Hue dimmer can operate the bulbs without the internet. Is this correct?
I would definitely add the bulbs to the hue bridge instead of directly to your ST hub. That’s the correct way the integration is supposed to work because hue uses ZLL protocol which makes for terrible repeaters in your Zigbee mesh. Keeping them secluded to the hue bridge will make for a much stronger mesh (for both hue and ST) and will certainly simplify everything for you.
As @saosinx88 said, it is better to have the bulbs on the Bridge because they are unreliable repeaters when connected directly to the smart things hub.
And to answer your question, yes, when the hue dimmer is connected to the hue Bridge, it operates locally.
FAQ: Do I need the Hue Bridge/Hub to Use a Hue Bulb with SmartThings?