Even more reason in my books not to skimp on the centre speaker
The best reason I can give people for using an identical center to there mains is that you never see anyone using 2 different left and right mains presumably because they share a lot of audio information between them so you want them to sound as similar as possible. Since a center seems in most material to share even more information with the L/R mains than those speakers even share between each other why would you want to use a different speaker unless you had to.
One thing, people switching or at least trying a matching vertical center might find is that I sounds very different and even might not like it. There is an appeal to the spread out sound of a horizontal center. Nothing wrong with that at all. I prefer QS8s for music even though theory says I should be using identical or as closely matched surrounds to my mains as I can, but since they are purpose built to reproduce ambient sounds I find they work better for me than direct radiators as surrounds.
When I switched from the VP150 to a vertical center I had already spent months using a phantom center so the change was not as drastic for me to just add another identical speaker. For people switching directly it will sound very different and quite possibly not as good since they are so use to hearing the horizontal center. And like I’ve said before there is an appeal to the way a horizontal array spreads the sound out across the screen. I think JC from Axiom is using 2 M22s laying horizontally above his screen. I tried and liked this a lot for movies but it didn’t work at all for music IMO.
