To answer your question, yes, you will get a lot from the addition of one or several channels. Adding channels gives the potential for improved sound, but...that all depends on execution.
2-channel vs 3-channel/5channel
I have been enjoying some B&W N802s for movie watching in 2 channel. A real pleasure. My question is, will I gain a lot of enjoyment by going through the complication/pain of setting up 3.1/5.1 or is 2 channel "enough" for movies.