Which speakers will fill 5,000 cubic ft coherently

I have a similar difficult room and have solved the issue with Tyler Woodmeres go to the website and look at the speaker, Bass drivers top and bottom, mid and treble array at ear level these speakers will solve your large room needs without taking up much floorspace....

The big Sound-Labs would love a room like yours.

The accuton drivers are not well known for playing loud/dynamically. So it is not surprising that a two way with these drivers might struggle in a large space. To me I don't think you need to go overkill - most equivalent price range three or four ways would make you much happier, IMHO.

I am not sure you need to go overkill but if you want beauty and assurance that you will be able to fill the space then Dynaudio Temptations, Wilson Alexandrias, Evolution MM3's would all do it without a single doubt in my mind.

You need to better specify what volume level you desire. You should also state what amp(s) you would be using.

80-90 db, Atma-Sphere MA 2.2 OTLs, 220 WPC.