I will never seriously consider a sub as an option again. For me, stereo=2.0.
You have a large music collection, and you must by now be an experienced critical listener. I really doubt you will be happy with those mirage speakers for a host of reasons. I would hazard an educated guess that bracing is the least of their problems.
Now for closed box and ported enclosures I use extensive bracing, but you have to be careful. B & W have shown that extensive bracing such as in their matrix speakers, causes an uneven load to the drivers, and has to be taken into consideration in the design. Thick braces have even been known to act as reflex ports. Since I listen to TL speakers, I have to use bracing very judiciously, as a lot of bracing kills the pipe.
I'm not so sure your view on subs is totally off base. A sub adds a crossover which ever way you look at it. In an awful lot of situations that is going to be a very uncontrolled and unpredictable crossover.
Now you asked about more speakers with eight inch two way design. That is a tough one, because the size of the driver makes the crossover problematic. I wasted time this morning going through lots of currently available 8 inch drivers. Only two cost effective drivers, one from Peerless and one from SEAS showed promise. One high priced unit from Morel was in the running.
Now I think another of the reasons for your preference for the eight is that the larger cone diameter will make the diffraction baffle loss start at a lower frequency.
Now it is easier to make 6.5 and 7 inch drivers behave better in the 1K to 6k range. Remember a driver has to have good behavior above crossover frequency, or else the crossover becomes more complex and costly.
There are now lots of 6.5 inch drivers that don't cost a fortune, that can be tuned to the 30 to 40 Hz range. If you make a speaker with two of those as a 2 1/2 way design, then you are well on the way to what you desire. Apart from movie sound effects and large pipe organs, well designed and voiced speakers with F3 closed below 55 Hz and ported in the low forties, give a very satisfying musical experience. That is why those types of design remain so popular.