FilmMixer at AVS is hoping to mix a movie in 348.8. Thanks to the the technology created by Iosono. He said the Mann theater in LA has it setup, and that just the demo with raindrops in the forest is amazing because it actually sounds like raindrops are hitting your shoulders.
I like matrixing my movies. Not my stereo music. But even for mch BDs do I just leave plIIx on. If people are such purists about applying an algorithm, then they would be hypocrites to upconvert their video.
There is another respectable poster at the aforementioned forum, and he recounted an interesting story. At an audiophile meeting, a certain person was blown away by the imaging from a 2ch source. He wasn't aware that there was Meridian processing going on. When he found out that the center speaker was being used, via algorithm, he stood up, pointed his finger at it, and exclaimed, "hey, that's cheating!". I mean, if it sounds good why not. Of course for many here that don't like the way these things sound, of course you ought to leave it off.
Lastly, many/most surround effects in movies are often mixed with height involved. Most movies you watch at home are simply using the movie theater mix. This is not even getting into the setups that they use to mix. I'm not talking about this like I'm an expert, because I'm always learning like anyone else here, and welcome further discussion. Cheers.