Originally Posted by MrLabGuy

Ceiling speakers don't make bad surrounds. Usually the information sent to the rear speakers is filler so you can get away with some cost cuts. The mains are important and also critical is get a center channel that matches the front mains as close as possible.

When considering Movie mode 90% of the movie will emanate from the center channel. Dialog is critical and most people scrimp on the center channel for large mains and wonder why they can't understand what is being said in the movie.