I’m planning on hanging onto my Swarm subs (2x 12″ sealed Rhythmik plus 1 dual 10″ DIY 600W sealed sub) so I’m not terribly concerned with bass (plus I have soffit absorbers around about 30% of the room ceiling and floor periphery)
Roger sent me a corrected table of panel sizes (there are some errors on the website and Audio Asylum). There is quite a bit less difference between the 745 and 645 footprint than I originally thought–only 4″ wider for the 745, although the U745 base is quite a bit deeper. So it really comes down to the visual impact vs. efficiency/bass.
I have a question into Constantine Soo who wrote a (several, actually) swooning review on Sound Labs. Roger recommended larger panels to him, but he decided to go with 645s for similar reasons to me. He stepped up from 545 to 645. I’ve asked whether, after almost a year with his speakers, does he have any regrets going with speakers smaller than Roger recommended.