Marsilians, for the specific issues with the centre channel there is a patented design called Vertical Array. Though this also looks externally like a regular centre channel, a vertical array speaker completely removes horizontal radiation of the listening area, A pair of baffle boards are mounted to a vertical array with small diameter speakers, in symmetrical opposition. The boards are kind of sealed at the rear, while the front are open to a predetermined width.
This is one of the reasons I purchased Aperion Audio's 533C VAC (now 5C VAC), one of the few companies that makes what is called the Vertical Array Centre Channel or VAC.
Cheers
