No one is saying that a vertically arrayed VP180 won’t sound good. You asked if it would sound better than an M80 which is very unlikely. I have not heard that comparison but can say that no speaker manufacture I know of puts a tweeter at the top and bottom of a vertical cabinet. Not even Axioms M80 which has both tweeters at the top. There’s a reason for this.
However, that doesn’t mean that a vertically arrayed VP180 won’t sound good. It might even sound better than a horizontally arrayed VP180 assuming you are basing sound quality on average frequency variation as one moves off axis. Audioholics did a test of various horizontal speakers with redundant drivers and found that in all cases arraying them vertically gave a better off axis frequency response. Some designs more than others. One thing to note is that a $115 vertical bookshelf speaker beat every horizontally arrayed horizontal center they tested. Only one horizontal center arrayed horizontally costing $2,500 equaled off axis performance of the $115 bookshelf speaker.
http://www.audioholics.com/education/loudspeaker-basics/vertical-vs-horizontal-speaker-designsMy own ears told me this when I first got my VP150 which is why I switched to an M80 center. Since then I’ve tested M22 and M2 speakers as centers and found they both beat the crap out of the VP150 arrayed either vertically or horizontally.
That doesn’t mean a horizontal array of drivers can’t sound good. Even me the vertical center nazi of the forum admit that there are time during movies and video games where a horizontal array of speakers creates a “wall-of-sound” that can give a more “movie-theater-like” performance that sounds quite impressive. I’ve even considered getting a VP180 and mounting it on a swivel so I can change it’s orientation between vertical and horizontal to have the best of both worlds but I’m just to lazy to try it since my M80 center already sounds so good.
