Should I use remodel or new construction recessed fixtures when installing a new ceiling?
Scenario #4

I would just remove all the old drywall and use new construction fixtures. It may seem like a lot of work but all these other problems go away. Plus my "drywall guy" would throw a hissy fit trying to finish a layer over another layer with a texture. The drywall won't lay flat like it should and finishing will cost you more money or it won't look right.  

Pulling down old drywall goes a lot faster than you think, especially if it is nailed instead of screwed. Once you get started large pieces can be pulled down.

One problem is the ceiling drywall is usually installed first so the wallboard is supporting it (trapping it) at the edge of the room. While pulling it down the wallboard could be damaged if it is not cut loose. Replacing it will require inserting the new ceiling drywall above the wallboard.

Good luck!