I was mentioning the migration of my Hue setup to HE just recently and someone mentioned that one of the reasons for keeping them on the bridge is to do with the different variation of the Zigbee protocol, which can play havoc I believe when mixing them with devices that use the other one, I think it is ZLL and ZHA. Since I have ported my lights and motion sensors to my new C-7 and most of my Samsung contact sensors and buttons are on my C-4, I think the recommendation in my situation is to keep these the way they are, and not port the Samsung devices over to the C-7 alongside the Hue devices. My situation is also a little different to yours in that I have the dimmers connected to a Conbee2 stick, not to HE directly.
This was one of the comments I was thinking of...
