Why do you need an additional nest camera if you already have a CC camera system with ethernet cameras? (Genuinely curious, because I have neither of those)
I wanted camera's in the garage and back yard on at all times (people have wandered around the back yard before). Nest also costs per camera, so it would get expensive as well.
So it was a variety of issues and it was a compromise i was willing, or maybe forced, to do. I am happy with just the closed camera system and sending footage offsite, alerts and logging on with my VPN if needed.