Hello Martin,
The Panasonic screamed, "Hey, I'm over here," likely because of its horrible coloration, and our ears are particularly acute about coloration on human voices. No hard feelings toward Panasonic, but most Japanese-branded speakers are fairly crummy (I've been to Japan numerous times and they just don't "get" speaker design, which is great for American, Canadian and British speaker companies). Panasonic, Sony, Yamaha, etc. do fine design in many other areas.
You could try a third M3ti or VP100 on a stand of some kind under the screen when you view DVDs. Don't put it on the floor. As JohnK mentioned, it will anchor the dialog for viewers to the sides. Having the dialog appear off-screen to one side for off-axis listeners, which will result if you do not use a center channel, is most disconcerting.
Regards,
