In Polk's case, they say it improves imaging. I don't recall what their documentation said because I sold them years ago, but I had them setup with a wide spacing but not too far from the listener, with the tweeters on the outside. This gave a nice, wide stage. With them on the inside, I had to toe them less and the mids suffered a bit as a result (these speakers were very picky about placement). With a larger room inside may have worked differently.