Hi,
It will be better to have different scenes. But it will mean more work to debug and create a proper memory friendly management solution.
Turning things on and off is ok-ish, but will require toomuch initial loading time, that's the trouble, then at runtime, having things turned off do not affect performances but is rarely the final solution simply because the scene is too big to manage during development and too big to load the first time.
Bye,
Jean