Thanks Jim. If you take a raw image and edit in PS as a smart object, you're opening that image in ACR. It becomes a raw layer when opened in PS. So let's say I process that (RAW) smart object for the sky. I can then open a new smart object via copy. This creates a new RAW layer that I can process for the foreground. So many more options using this to get the result you want. I'm not yet done learning this technique as there's much more to it. For now, keeping it simple but I like the result.
In LR, I would sometimes feather my sky selection but other times use the sky selection tool. On the latter, over processing will lead to a bright halo on the horizon. Sometimes this can fixed using a negative clarity brush on the horizon line but its success depends on how bad the horizon halo is.
Thanks Bob, I thought that a Smart Object would be one way to do what you were describing, but since you didn't say Smart Object, I thought maybe there was some secret new technique I hadn't heard of yet instead.

Glad to see that is what was done.
In LR, both feathering and using the Sky Selection tool in my mind is not good for selecting and editing the sky seperate from the ground as both feather and both will cause halo's. If you just do a Quick Selection on the sky and don't use any feathering, that will result with no halo's. But of course the Quick Selection tool has it's limits. And the Sky Selection tool does have it's purposes and uses, but one has to watch out for those halo's as you mentioned.
That's great you are using the Smart Objects now, they are the most powerful, because as you said you can edit them in the ACR tool in Photoshop.
I look forward to seeing the results of you using Smart Objects more with your B&W as this image here is just outstanding!