@doni @daledeee1 @bjesien - appreciate the thoughtful suggestions. I have my eye on a pair of Volti Razz. I would definitely look at the Forte IV's but they are to wide for the tight space on the right side based on furniture layout.
Plus they wouldn't fly with the wife- low WAF :) factor. The Razz fit the space and are only 2 inches wider than the Zu's I have.
I absolutely love my F8 and don't want to part with it at this point. It sings with my system and I am 100% confident that an upgraded speaker will take it up a level. When its time the Pass XA 25 would be my choice. I have spied that on for $3K and doubt it will last.
@wolf_garcia - yes, check out the X25's on USAM There are 2 available - $3250 and $3600. Also note your assumption is incorrect. System is inside a brick walled house with plenty of room from the side of the speakers to the space leading to the parapet walls, cannon ports and moat.