I'm using the two in conjunction, because MCCC does things which Neighborhood stories does not.
I've left all of my MCCC settings the same, but turned down the pregnancy rate to be much, much lower (set it at 1%) to see how well the new Neighborhood stories functions for this instead.
Beyond that, I've left MCCC to handle moving Sims around and marrying them off and disabled the moving features of Neighborhood stories because the stories feature doesn't include marriage other than the rare "phone calls" about it that we've had for a long time. It also isn't clear how well neighborhood stories will do at splitting households up for the move out feature.
I also left MCCC in charge of any career changes, because it is fully integrated with the ability to fill careers as 'needed' so the game doesn't have to make all new sims for that, whereas Neighborhood stories just uses the setting to create stories.
I also left MCCC set to automatically move out elders into homeless 'elderly' households, and then set Neighborhood stories for those households to allow accidental deaths and retirement, two settings for Neighborhood stories which I'm not using for any other households. It's working quite well to thin out the elderly population before they actually die of old age. So in this regards, neighborhood stories is enhancing MCCC. :lol:
At this point I've played through nearly 3 sim weeks with the two running side by side. MCCC is still working normally and the Neighborhood stories is doing its thing too. You can feel comfortable using the two together, just be aware of what you have each set to, so they aren't working against each other.