Thanks to everyone who replied.

I have an odd no-name main panel in the house, so the way I go may
depend on parts availability. They're still constructing in the
neighborhood. I may flag down the electrician and see if I can buy the
breaker from him.

I hadn't though about the extra main switch being an advantage. I
guess I'll leave it in.

I have an extra set of lights that won't be going through the subpanel.
I'll lose the main lights, but still have plenty to see.

brian