Dave: Had experiecne at Dobly and THX, Lucasfilm.
In 2007 for 5.1, HT, We used in wall Dayton for the surrounds LR/RR, DIY built 1 cu ft reflex with PHL woofers ands RAAL ribbon tweeters, DIY Xover 4p. Linkewitz-Riley.
Center was simple bookshelf spker, plus subwoofer.
Center wsa small enough to sit on top of Subwoofer.
As center is usually the dialog and just voice, it is not so critical.
GREAT sound super imaging and highs from RAAL ribbons....
Enjoy,
Jon
j