Spray infiltrates heating/cooling duct work. Roll. I would never spray in occupied house.

I wouldnt spray either. I would roll the ceilings. That overspray will be everywhere, no matter how careful. My last house had been sprayed inside and outside. It took 2 full years, to finally get rid of all that overspray. At that time, no duct work to worry about, thank goodness. The central heat and air, happened in the 3rd year.

With roller its better

I would probably have a pro roll it.

Now that I've said that, I did spray a living room ceiling with my BILs help once. And, it turned out great.

The lath and plaster ceiling in that 1926 bungalow was highly textured (think whipped and curls). Like peaked meringue on a pie is the only way I can think to describe it. It took a roller with depth like sheepskin to paint it, making the roller HEAVY and the process tedious - I had also done that room by hand.

Coved ceiling with crown molding all the way around the room. I taped drop cloths to the molding draped down the walls and covered the doorways, flooring. Shhhh! I didn't even remove artwork or large furniture, only lamps, things that could be tipped.

BIL was experienced with the sprayer. We had no errors or problems. It took longer to prepare the room than to paint. I spent a fortune on drop cloths, didn't go with the cheapest, imagining getting tangled up in flimsy plastic or tearing it.

I'm only admitting having done it. I would not necessarily recommend it and haven't found reason to do it again - we no longer have that house and I don't think I could justify spraying the traditional ceilings in this one.